CN113381844A

CN113381844A - Method and device for configuring number of symbols of downlink additional demodulation reference signal

Info

Publication number: CN113381844A
Application number: CN202010115315.6A
Authority: CN
Inventors: 张路; 刘继民
Original assignee: Nokia Shanghai Bell Co Ltd
Current assignee: Nokia Shanghai Bell Co Ltd
Priority date: 2020-02-25
Filing date: 2020-02-25
Publication date: 2021-09-10
Anticipated expiration: 2040-02-25
Also published as: CN113381844B

Abstract

A method for configuring the number of symbols of a downlink additional demodulation reference signal is disclosed. In the method, a current configuration of a downlink, an index reflecting a signal-to-interference-and-noise ratio level of the downlink, and one or more candidate configurations of the downlink related to the current configuration may be determined, and if the determined one or more candidate configurations include a candidate configuration satisfying a condition related to the aforementioned index, the current configuration may be replaced with the candidate configuration. Related apparatus and computer readable storage media are also disclosed.

Description

Method and device for configuring number of symbols of downlink additional demodulation reference signal

Technical Field

The present disclosure relates to a method, apparatus, and computer-readable storage medium for configuring the number of symbols of a downlink additional demodulation reference signal.

Background

For example, for a downlink of a communication system such as a New Radio (NR) system, one or more additional DMRS symbols may be configured in addition to a Demodulation Reference Signal (DMRS) symbol carried in front.

Disclosure of Invention

In one aspect, a method for configuring the number of symbols of a downlink additional demodulation reference signal is disclosed. The method can comprise the following steps: determining a current configuration of a downlink, wherein the current configuration may include a current number of additional DMRS symbols and a current level of Modulation and Coding Scheme (MCS); determining an index reflecting a Signal to Interference plus Noise Ratio (SINR) level of the aforementioned downlink; determining at least one candidate configuration of a downlink related to the aforementioned current configuration, wherein each candidate configuration may include less than the aforementioned current number of additional DMRS symbols and/or a MCS higher than the aforementioned current level; and replacing the current configuration with the first candidate configuration if the at least one candidate configuration includes a first candidate configuration that satisfies a condition related to the indicator. For example, the method may be performed at the access network side (e.g. in a base station).

In some embodiments, the conditions related to the aforementioned indicators may include: the index is higher than a sum of an SINR required for the candidate configuration to achieve a specified Block Error Rate (BLER) target and an SINR variance resulting from changing from the current configuration to the candidate configuration, the SINR variance being a difference between an SINR required for the candidate configuration to achieve the specified BLER target and an SINR required for the current configuration to achieve the specified BLER target.

In some embodiments, the aforementioned at least one candidate configuration may further include a second candidate configuration that satisfies the aforementioned condition, and the aforementioned first candidate configuration provides a greater throughput gain than the aforementioned second candidate configuration.

In some embodiments, the aforementioned first candidate configuration comprises less than the aforementioned current number of additional DMRS symbols and the same MCS as the aforementioned current level.

In some embodiments, the aforementioned at least one candidate configuration may further include a second candidate configuration satisfying the aforementioned condition, the level of the MCS of the aforementioned first candidate configuration is the same as the level of the MCS of the aforementioned second candidate configuration, and the number of additional DMRS symbols of the aforementioned first candidate configuration is less than the number of additional DMRS symbols of the aforementioned second candidate configuration.

In some embodiments, the level of the aforementioned first candidate configured MCS is higher than the aforementioned current level.

In some embodiments, the aforementioned at least one candidate configuration may further include a second candidate configuration satisfying the aforementioned condition, the MCS of the aforementioned first candidate configuration is higher than the level of the MCS of the aforementioned second candidate configuration, and the number of additional DMRS symbols of the aforementioned first candidate configuration is less than or equal to the number of additional DMRS symbols of the aforementioned second candidate configuration.

In some embodiments, the at least one candidate configuration may further include a second candidate configuration satisfying the condition, wherein a level of an MCS of the first candidate configuration is higher than a level of an MCS of the second candidate configuration, a number of additional DMRS symbols of the first candidate configuration is greater than a number of additional DMRS symbols of the second candidate configuration, and a throughput gain that may be obtained if a level of an MCS of the second candidate configuration is raised to the level of the MCS of the first candidate configuration is higher than a throughput loss that may be obtained if the number of additional DMRS symbols of the first candidate configuration is increased from the number of additional DMRS symbols of the second candidate configuration.

In some embodiments, the Indicator may include a Channel Quality Indicator (CQI) measured and reported by the terminal device in a case where the terminal device of the downlink moves within a cell.

In some embodiments, the aforementioned indicator may comprise an SINR (Synchronization/PBCH Signal block SINR, SS-SINR) of a Synchronization and broadcast Signal block associated with the target cell or an SINR (Channel State Information reference Signal SINR, CSI-SINR) of a Channel State Information reference Signal measured and reported by the aforementioned terminal device in case of an inter-cell handover occurring at the aforementioned terminal device of the downlink.

In some embodiments, in a case where the terminal device in the downlink performs inter-cell handover, the indicator may include a ratio of Reference Signal Receiving Power (RSRP) measured by the terminal device for the target cell to a sum of RSRPs measured by the terminal device in all detectable cells except the target cell and a sum of additive white gaussian noise average Power of the terminal device.

In some embodiments, the mobile speed may be divided into a plurality of consecutive levels, the current number of the currently configured additional DMRS symbols is generally equal to or may be smaller than a typical configuration number of additional DMRS symbols predetermined for a level to which the mobile speed of the terminal device in the downlink belongs, the at least one candidate configuration refers to a candidate configuration when the level to which the mobile speed of the terminal device belongs is not changed, and the number of the additional DMRS symbols of the at least one candidate configuration is smaller than or equal to the typical configuration number.

In some embodiments, the Doppler Frequency Offset (DFO) may be divided into a plurality of consecutive ranges, the current number of the currently configured additional DMRS symbols is generally equal to or may be smaller than a typical configuration number of additional DMRS symbols predetermined for a range to which the DFO of the terminal device in the downlink belongs, the at least one candidate configuration is a candidate configuration when the range to which the DFO of the terminal device belongs does not change, and the number of the at least one candidate configuration of additional DMRS symbols is smaller than or equal to the typical configuration number.

In another aspect, an apparatus for configuring the number of symbols of a downlink additional demodulation reference signal is also disclosed. The apparatus may include: a first module configured to determine a current configuration of a downlink, the current configuration including a current number of additional DMRS symbols and a current level of MCS; a second module configured to determine an index reflecting the SINR level of the aforementioned downlink; a third module configured to determine at least one candidate configuration of the aforementioned downlink related to the aforementioned current configuration, each candidate configuration comprising less than the aforementioned current number of additional DMRS symbols and/or a MCS higher than the aforementioned current level, and to replace the aforementioned current configuration with the aforementioned first candidate configuration if the aforementioned at least one candidate configuration comprises a first candidate configuration that satisfies a condition related to the aforementioned indicator. For example, the apparatus may be part of an access network (e.g., a base station).

In some embodiments, the conditions related to the aforementioned indicators may include: the indicator is higher than the sum of the SINR required for the candidate configuration to achieve the specified BLER target and the SINR variance resulting from changing from the current configuration to the candidate configuration, the SINR variance being the difference between the SINR required for the candidate configuration to achieve the specified BLER target and the SINR required for the current configuration to achieve the specified BLER target.

In some embodiments, the aforementioned at least one candidate configuration may further include a second candidate configuration satisfying the aforementioned condition, the level of the MCS of the aforementioned first candidate configuration is higher than the level of the MCS of the aforementioned second candidate configuration, and the number of additional DMRS symbols of the aforementioned first candidate configuration is less than or equal to the number of additional DMRS symbols of the aforementioned second candidate configuration.

In some embodiments, the aforementioned second module may be configured to receive, as the aforementioned indicator, CQI measured and reported by the aforementioned terminal device in a case where the aforementioned terminal device of the downlink moves within a cell.

In some embodiments, the aforementioned second module may be configured to receive, in a case where the aforementioned terminal device of the downlink performs inter-cell handover, as the aforementioned indicator, an SS-SINR or CSI-SINR associated with the target cell measured and reported by the aforementioned terminal device.

In some embodiments, the second module may be configured to determine, as the indicator, a ratio of RSRP measured by the terminal device for the target cell to a sum of RSRP measured by the terminal device for all detectable cells except the target cell and an additive white gaussian noise average power of the terminal device, in a case where inter-cell handover occurs to the terminal device for the downlink.

In some embodiments, the mobile speed may be divided into a plurality of consecutive levels, and the first module configures the current number of the currently configured additional DMRS symbols to be less than or equal to (usually, to be equal to) a typical configured number of additional DMRS symbols predetermined for a level to which the mobile speed of the terminal device in the downlink belongs. The at least one candidate configuration determined by the third module is a candidate configuration when the level to which the moving speed of the terminal device belongs does not change, and the number of the additional DMRS symbols of the at least one candidate configuration is less than or equal to the typical configuration number.

In some embodiments, the DFO may be divided into a plurality of consecutive ranges, and the first module configures the current number of the currently configured additional DMRS symbols to be less than or equal to (typically, equal to) a typical configured number of predetermined additional DMRS symbols for a range to which the DFO of the terminal device on the downlink belongs. The at least one candidate configuration determined by the third module is a candidate configuration when the range to which the DFO of the terminal device belongs does not change, and the number of the additional DMRS symbols of the at least one candidate configuration is less than or equal to the typical configuration number.

In another aspect, an apparatus for configuring the number of symbols of a downlink additional demodulation reference signal is also disclosed. The apparatus may include at least one processor and at least one memory. The at least one memory may include computer program code, and the at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to perform: determining a current configuration of a downlink, wherein the current configuration may include a current number of additional DMRS symbols and a current level of MCS; determining an index reflecting the SINR level of the aforementioned downlink; determining at least one candidate configuration of the aforementioned downlink that is related to the aforementioned current configuration, wherein each candidate configuration may include less than the aforementioned current number of additional DMRS symbols and/or a MCS that is higher than the aforementioned current level; and replacing the current configuration with the first candidate configuration if the at least one candidate configuration includes a first candidate configuration that satisfies a condition related to the indicator. For example, the method may be performed at the access network side (e.g. in a base station). For example, the apparatus may be part of an access network (e.g., a base station).

In some embodiments, the aforementioned indicator may comprise a CQI measured and reported by the aforementioned terminal device in the case where the aforementioned terminal device of the downlink moves within a cell.

In some embodiments, the aforementioned indicator may comprise an SS-SINR or CSI-SINR associated with the target cell measured and reported by the aforementioned terminal device in the event of an inter-cell handover occurring at the aforementioned terminal device for downlink.

In some embodiments, in the case of an inter-cell handover of the terminal device in the downlink, the indicator may include a ratio of an RSRP measured by the terminal device for the target cell to a sum of RSRPs measured by the terminal device in all detectable cells except the target cell and a sum of additive white gaussian noise average powers of the terminal device.

In some embodiments, the DFO may be divided into a plurality of consecutive ranges, the current number of the currently configured additional DMRS symbols is generally equal to or may be smaller than a typical configuration number of additional DMRS symbols predetermined for a range to which the DFO of the terminal device in the downlink belongs, the at least one candidate configuration refers to a candidate configuration when the range to which the DFO of the terminal device belongs does not change, and the number of the additional DMRS symbols of the at least one candidate configuration is smaller than or equal to the typical configuration number.

In another aspect, a computer-readable storage medium having instructions stored thereon is also disclosed, the instructions operable to cause an apparatus to: determining a current configuration of a downlink, wherein the current configuration may include a current number of additional DMRS symbols and a current level of MCS; determining an index reflecting the SINR level of the aforementioned downlink; determining at least one candidate configuration of the aforementioned downlink that is related to the aforementioned current configuration, wherein each candidate configuration may include less than the aforementioned current number of additional DMRS symbols and/or a MCS that is higher than the aforementioned current level; and replacing the current configuration with the first candidate configuration if the at least one candidate configuration includes a first candidate configuration that satisfies a condition related to the indicator. For example, the method may be performed at the access network side (e.g. in a base station). For example, the apparatus may be part of an access network (e.g., a base station).

Drawings

Fig. 1 shows an example of a cell in a communication system and a terminal Equipment or User Equipment (UE) entering the cell.

Fig. 2 illustrates an example method for configuring downlink to a specified UE in an embodiment of the present disclosure.

Fig. 3 illustrates an example of one correspondence relationship between DFO, mobile speed level, and the number of additional DMRS symbols in an embodiment of the present disclosure.

Fig. 4 shows an example of a set of curves representing the "BLER versus SINR relationship" for all MCS levels.

Fig. 5 illustrates an example apparatus for configuring downlink to a designated UE in an embodiment of the disclosure.

Fig. 6 illustrates an example apparatus for configuring downlink to a designated UE in an embodiment of the disclosure.

Detailed Description

For a cell in a communication system such as an NR system, the number of additional DMRS symbols for downlink may be statically configured according to an operation and maintenance (O & M) setting, for example. For example, in the example of fig. 1, for cell 100, it may be statically configured with reference to O & M settings: 2 additional DMRS symbols may be configured. Then, for the downlink from the base station 110 to any

UE

120, 130, 140 or 150 within this cell 100, 2 additional DMRS symbols may be configured. In further examples, the number of additional DMRS symbols available for the downlink may also be 0 (i.e., additional DMRS symbols are disabled), 1, 3, or more.

By configuring more additional DMRS symbols, a higher demodulation reference signal symbol density can be provided, so that, for example, better channel estimation, more accurate DFO estimation, better DFO compensation, and the like can be obtained. However, more resources are used for additional DMRS symbols, e.g., peak data rate may be reduced.

In addition, for the additional DMRS symbols, a static configuration may be generally adopted, for example, a fixed number of additional DMRS symbols may be uniformly configured for all UEs in a cell, for example, in a cell unit. However, for different UEs within the same cell, due to differences in hardware quality, processing capability, moving speed, etc. of the respective UEs, the static configuration manner in units of cells may work well for some UEs, but may work poorly for other UEs, or may not be necessary for some UEs.

Therefore, a solution is desired that can dynamically configure or adjust the number of additional DMRS symbols for any given UE according to the actual situation of the UE (e.g., the UE's mobility speed level, DFO level, channel quality, etc.).

Fig. 2 illustrates an example method 200 for configuring the number of symbols of a downlink additional demodulation reference signal of an embodiment of the present disclosure.

As shown in fig. 2, the example method 200 may include:

step 210, determining a current configuration of a downlink, wherein the current configuration may include a current number of additional DMRS symbols and a current level MCS;

step 220, determining an index for reflecting the SINR level of the downlink;

step 230, determining at least one candidate configuration of the downlink related to the current configuration, wherein each candidate configuration may include less than the current number of additional DMRS symbols and/or MCS higher than the current level; and

in step 240, if the determined at least one candidate configuration includes a first candidate configuration that satisfies the condition related to the metric determined in step 220, the current configuration is replaced with the first candidate configuration.

In this example method 200, for a downlink from a base station to a given UE, it may be determined whether the current channel quality is good enough based on an index reflecting the SINR level of the downlink. In case the current channel quality is judged to be good enough, candidate configurations that meet, for example, pre-specified performance indicators may be selected to replace the current configuration, thereby enabling adaptive configuration of the downlink for the specified UE.

For example, in the example method 200, at least one of the number of additional DMRS symbols and the MCS level may be adjusted such that, compared to the current configuration, the candidate configuration considered and ultimately used to replace the current configuration may employ fewer additional DMRS symbols with the MCS level remaining unchanged, may employ a higher order MCS with the number of additional DMRS symbols unchanged, may employ fewer additional DMRS symbols with the higher order MCS at the same time, and may even employ a higher order MCS but more additional DMRS symbols (at which point the throughput gain due to MCS level boosting is higher than the throughput loss due to the use of more additional DMRS symbols). The smaller the number of additional DMRS symbols configured, may mean that more resources can be allocated to data to be actually transmitted. Therefore, by reducing the number of additional DMRS symbols, a greater throughput gain, a higher resource utilization, and the like can be obtained. In addition, a higher level of MCS employed may generally mean a higher rate. Therefore, by increasing the MCS level, a larger throughput gain and the like can be obtained. That is, greater throughput gain, higher resource utilization, etc. can be achieved through the adaptive configuration of the example method 200.

More details of the example method 200 are described below.

As shown in fig. 2, in step 210 of the example method 200, for a downlink of a given UE, a current configuration of the downlink may be determined, where the current configuration may include a number of additional DMRS symbols currently used for the downlink from the base station to the given UE.

For example, when initially configuring the downlink for the UE or reconfiguring the downlink for the UE, the number of the additional DMRS symbols employed in the current configuration may be determined according to at least one index, such as a mobility speed level of the UE, a DFO of the UE, and the like.

For example, all possible DFO values may be divided into a plurality of consecutive DFO ranges. As shown in fig. 3, since the maximum number of configurable additional DMRSs is 3, the entire DFO range may be previously divided into 4 consecutive DFO ranges [0Hz, DFO₁Hz)、[DFO₁Hz,DFO₂Hz)、[DFO₂Hz,DFO₃Hz) and [ DFO₃Hz,DFO_maxHz]So that DFO is generated₁Hz、DFO₂Hz、DFO₃Hz and DFO_maxHz respectively corresponds to the moving speed S₁km/h、S₂km/h、S₃km/h and S_maxkm/h. Further, for the DFO range [0Hz, DFO₁Hz) or a moving speed class [0km/h, S₁km/h), typically 0 additional DMRS symbols may be configured (i.e., DMRS is not configured); for DFO Range [ DFO₁Hz,DFO₂Hz) or moving speed class S₁km/h,S₂km/h), typically 1 additional DMRS symbol may be configured; for DFO Range [ DFO₂Hz,DFO₃Hz) or moving speed class S₂km/h,S₃km/h), typically 2 additional DMRS symbols may be configured; for DFO Range [ DFO₃Hz,DFO_maxHz]Or a moving speed class S₃km/h,S_maxkm/h]Typically, 3 additional DMRS symbols may be configured.

The serving base station may then evaluate at least one of a DFO and a mobility speed level of the UE based on the received channel Sounding Reference Signal (SRS), or by any other suitable method, the current number of currently configured additional DMRS symbols for the downlink of the UE being generally equal to a typical configured number of additional DMRS symbols predetermined for at least one of the mobility speed level and the DFO of the UE. For example, if the UE is determined to have a mobility speed level of S based on SRS₁km/h,S₂km/h) or its corresponding DFO range is [ DFO₁Hz,DFO₂Hz), then typically 1 additional DMRS symbol may be configured, and then 1 additional DMRS symbol is employed in the current configuration for the downlink of that UE.

By dividing the mobility speed level of the UE into a plurality of consecutive levels or dividing the DFO of the UE into a plurality of consecutive ranges, and predetermining a typical configuration number of additional DMRS symbols for each level or range, more efficient configuration can be enabled for a given UE. For example, for different UEs in the same cell, different configurations using different numbers of additional DMRS symbols can be selected according to their different characteristics, so that for different UEs, for example, a better tradeoff between channel estimation/DFO estimation and resource utilization can be obtained.

In further examples, the current number of currently configured additional DMRS symbols may be less than a typical configured number of additional DMRS symbols predetermined for at least one of a mobility speed level and a DFO of the UE. For example, if the UE is determined to have a mobility speed level of S based on SRS₂km/h,S₃km/h) or its corresponding DFO range is [ DFO₂Hz,DFO₃Hz), then typically 2 additional DMRS symbols may be configured, then 0, or 1, additional DMRS symbols may be employed in the current configuration for the downlink of that UE.

Additionally, the number of additional DMRS symbols in the current configuration may also be a number that is updated after applying the example method 200 one or more times. For example, for a moving speed level of [ S ]₂km/h,S₃km/h) or a DFO range of [ DFO₂Hz,DFO₃Hz), initializes the number of additional DMRS symbols for the downlink of the UE to 2, and reduces the number of additional DMRS symbols from the current number (2) to 1 by applying the example method 200; then, one or more trigger conditions (e.g., the UE moves to a specific location area within a cell, etc.) may be preset, and the example method 200 may be applied again when such trigger conditions are satisfied, thereby further reducing the number of additional DMRS symbols from the new current number (1) to 0.

Additionally, in step 210 of the example method 200, for the downlink of a given UE, the current configuration may also include a level of MCS currently employed for the downlink to the given UE.

In one example, the levels of MCS available for the downlink may include levels 0-31, with levels 29-31 being redundant, then in the example method 200, the MCS may be adjusted upward or maintained unchanged at levels 0-28.

Similar to the number of additional DMRS symbols in the current configuration, the current level of the MCS in the current configuration may be configured when initially configuring the downlink for the UE or reconfiguring the downlink for the UE, or may be a level that is updated after applying the example method 200 one or more times.

Then, as shown in fig. 2, in step 220 of the example method 200, an index reflecting the SINR level of the downlink may be determined.

In various embodiments, the indicator may be any type, form, of indicator that can be used to reflect the SINR level or channel quality level of the downlink for the UE.

In one embodiment, for example, where the UE moves within a cell, the indicator may include CQI measured and reported by the UE, or the like. In this embodiment, existing signaling and processing flows can be utilized on the UE and base station sides, and thus, lower implementation costs can be achieved.

In one embodiment, for example, in the case of an inter-cell handover (handover) of the UE, the indicator may include the SS-SINR or CSI-SINR, etc. defined in 3GPP TS38.215 associated with the target cell measured and reported by the UE, e.g., the SS-SINR or CSI-SINR measured on the handed over target cell reported by the UE triggered by the measurement reporting trigger event a 4. For example, such SS-SINR or CSI-SINR can effectively reflect the SINR level of the downlink in the case where desired reference signals and undesired reference signals (i.e., interference signals) are not transmitted through orthogonal resources. In this embodiment, existing signaling and processing flows can be utilized on the UE and base station sides, and thus, lower implementation costs can be achieved.

However, in order to be able to obtain accurate detection results for desired reference signals, in some cases, required and unneeded reference signals may be intentionally configured to be transmitted on orthogonal resources, such that the aforementioned SS-SINR or CSI-SINR may not accurately reflect the SINR level of the downlink.

Thus, in one embodiment, for example, in the case of inter-cell handover of the UE, a ratio of the RSRP measured by the UE on the target cell relative to the sum of the RSRPs measured by the UE in all cells except the target cell detectable and the sum of the average powers of Additive White Gaussian Noise (AWGN) of the UE may be determined as an index for reflecting the SINR level of the downlink. For example, RSRP measured by the UE on a to-be-detected carrier corresponding to a target cell in a sector to which the target cell of handover belongs may be used as a first parameter, and a sum of one or more RSRPs measured by the UE on the same to-be-detected carrier in at least one neighboring sector of the sector and AWGN average power corresponding to the UE may be used as a second parameter. The ratio of the first parameter to the second parameter may then be used as an estimate of the SINR based on RSRP. Thereby, for example, when a desired reference signal and an undesired reference signal (i.e., an interference signal) are transmitted through orthogonal resources, an effective estimated value for SINR can be provided.

Then, as shown in fig. 2, in step 230 of the example method 200, at least one candidate configuration for the downlink of the UE may be determined. The candidate configuration refers to a configuration that can provide a greater throughput than the current configuration when the level to which the moving speed of the UE belongs and the range to which the DFO belongs are not changed.

Compared to the current configuration, the candidate configuration may employ fewer additional DMRS symbols with the MCS level being kept the same, or employ a higher order MCS with the number of additional DMRS symbols being kept the same, or employ fewer additional DMRS symbols and a higher order MCS at the same time, and may even employ a higher order MCS but employ more additional DMRS symbols (at this time, the throughput gain due to MCS level boosting is higher than the throughput loss due to the use of more additional DMRS symbols).

For example, if in the current configuration, the number of additional DMRS employed is 1 and the level of MCS employed is 27 (assuming the highest level of adjustability is 28), a candidate configuration using 0 additional DMRS symbols and MCS of level 27 (fewer additional DMRS symbols are employed while keeping the MCS level unchanged), a candidate configuration using 1 additional DMRS symbols and MCS of level 28 (higher level MCS is employed while keeping the number of additional DMRS symbols unchanged), and a candidate configuration using 0 additional DMRS symbols and MCS of level 28 (fewer additional DMRS symbols and higher level MCS are employed at the same time) may be determined.

In one embodiment, in step 230, all possible candidate configurations may be determined. In further embodiments, the partial candidate configurations may be determined based on some conditions. For example, for a current number of additional DMRS symbols employed in a current configuration and a current level of MCS employed and a given BLER target, an SINR may be determined in case of employing a typical configured number of additional DMRS symbols predetermined for at least one of a moving speed level and a DFO of the UE and an MCS level one level higher than the MCS of the current level. Then, if the indicator determined in step 220 is lower than the SINR, in step 230, one or more candidate configurations may be determined such that each candidate configuration maintains the current MCS level and employs fewer additional DMRS symbols than the current configuration. If the index determined in step 220 is higher than the SINR, then in step 230, the candidate configuration that selects a higher level MCS may be considered. Thus, the number of candidate configurations determined in step 230 may be reduced, thereby facilitating an increase in the processing efficiency of the example method 200.

Then, for example, it may be checked in step 230 or step 240 of the example method whether one or more of the candidate configurations determined in step 230 includes a candidate configuration that satisfies the condition associated with the metric determined in step 220.

As shown in fig. 2, if such a candidate configuration exists, the current configuration is replaced with the candidate configuration in step 240. This candidate configuration is also referred to herein as the "first candidate configuration".

As previously described, all possible mobile speed levels or DFO values may be divided into a plurality of contiguous ranges, and the base station may evaluate at least one of the DFO and mobile speed levels of the UE based on the received SRS or by any other suitable method, and then determine a current number of additional DMRS symbols in a current configuration for the downlink of the UE based on at least one indicator of the evaluated DFO and mobile speed levels for the UE, such that the current number of currently configured additional DMRS symbols is less than or equal to (typically equal to) a pre-determined typical configured number of additional DMRS symbols for at least one of the mobile speed levels and DFO of the UE.

For example, if all possible moving speed levels or DFO values are divided into K consecutive ranges (K is a natural number greater than 1), and the respective ranges are noted as 0 th to (K-1) th ranges in order of the moving speed levels or DFO values from low to high, and the moving speed level or DFO value of a UE belongs to the kth range (K is an integer greater than or equal to 0 and less than or equal to K-1), the number of configurable additional DMRS symbols does not exceed K (typical configuration is equal to K) for the downlink of the UE.

Thus, in some embodiments, for the kth range corresponding to the moving velocity level or DFO of a given UE, the aforementioned condition relating to the index determined in step 220 may be constructed with a "BLER to SINR relationship" for all MCS levels.

Fig. 4 shows an example of a set of curves representing the "BLER versus SINR relationship" for all MCS levels for the kth range, where BLER is on the vertical axis and SINR is on the horizontal axis. In such a curve set, each MCS level may have k +1 curves, corresponding to the case of using 0 additional DMRS symbols, … …, and k additional DMRS symbols, respectively.

For simplicity, in FIG. 4, assume that k ≧ 1 (so that each MCS level can have at least two curves to more easily illustrate implementations of the invention), then only curve C corresponding to MCS level m (m is an integer) and number of additional DMRS symbols k is shown₁And the MCS level is m and the number of the additional DMRS symbols is k '(0 ≦ k'<k) Corresponding curve C₂And the MCS level is m ' (m ' is an integer and m '>m) and additional DMRS symbols of number k₃And a curve C corresponding to an MCS level of m' and a number of additional DMRS symbols of k₄These 4 curves.

As shown in FIG. 4, for a given BLER target (i.e., the dashed line parallel to the horizontal axis in FIG. 4, e.g., 10)^-1) May be respectively on the 4 curves C₁、C₂、C₃And C₄Upper determination of 4 values of SINR_m,k(representing the SINR required to achieve a given BLER target with a configuration of M-level MCS and k additional DMRS symbols), SINR_m,k’(representing the SINR required to achieve a given BLER target with a configuration of M-level MCS and k' additional DMRS symbols), SINR_m’,k(representing the SINR required to achieve a given BLER target with a configuration of M' level MCS and k additional DMRS symbols) and SINR_m’,k’(representing the SINR required to achieve a given BLER target with a configuration of m 'level MCS and k' additional DMRS symbols).

Accordingly, from these 4 SINR values, 3 variance values can be determined: delta SINR_m->m,k->k’I.e. SINR_m,kAnd SINR_m,k’A difference therebetween, which may represent a degree of degradation of the SINR level that may result if the MCS level m is maintained unchanged and the number of additional DMRS symbols is reduced from k to k'; delta SINR_m->m’,k->kI.e. SINR_m,kAnd SINR_m’,kA difference therebetween, which may represent a degree of degradation of the SINR level that may be caused if the number of additional DMRS symbols is maintained and the MCS level is increased from m to m'; delta SINR_{m->m’,k->k’}I.e. SINR_m,kAnd SINR_m’,k’A difference between them, which may represent a degree of degradation of the SINR level that may result if the MCS level is raised from m to m 'and the number of additional DMRS symbols is reduced from k to k'.

Then, in some embodiments, the conditions to be checked relating to the index for reflecting the SINR level of the downlink of the UE may include: whether the indicator is higher than the sum of the SINR required for the candidate configuration to achieve the specified BLER target and the SINR variance due to the change from the current configuration to the candidate configuration, wherein the SINR variance is the difference between the SINR required for the candidate configuration to achieve the specified BLER target and the SINR required for the current configuration to achieve the specified BLER target. That is, in this embodiment, the sum of "SINR required for new configuration" and "degradation of SINR level that may be caused by applying new configuration" is considered, whereby a very reliable judgment condition can be provided so that data transmission performance/quality of the current downlink can not be degraded while configuring less resources and/or higher transmission rate.

In further embodiments, based on simplification of the foregoing conditions, the condition to be checked regarding the index for reflecting the SINR level of the downlink of the UE may further include: whether the indicator is higher than the SINR required for the candidate configuration to achieve the specified BLER target. In other words, if for a candidate configuration the indicator is higher than the SINR required for the candidate configuration to achieve the specified BLER target, the candidate configuration may be determined to fulfill the condition related to the indicator for reflecting the SINR level of the downlink of the UE.

In some embodiments, if there are multiple candidate configurations that satisfy the condition, the first candidate configuration selected in step 240 to replace the current configuration may be any candidate configuration that selects a condition that is satisfied, or may be one that can provide a greater throughput gain than one or more or all of the other candidate configurations that satisfy the condition (also referred to herein as "second candidate configurations").

In some embodiments, the first candidate configuration selected in step 240 for replacing the current configuration may employ fewer additional DMRS symbols and the same MCS level as the current configuration than the current configuration. If there are multiple candidate configurations that satisfy the condition, and each candidate configuration includes the same MCS level, the first candidate configuration for replacing the current configuration may be that candidate configuration that employs fewer additional DMRS symbols than one or more or all of the second candidate configurations.

In further embodiments, the first candidate configuration selected in step 240 to replace the current configuration may employ a higher level MCS than the current configuration. In the case where there are at least two candidate configurations that satisfy the condition, the first candidate configuration may be one or more or all of the following compared to the second candidate configuration: (1) that candidate configuration that employs the same level of MCS but fewer additional DMRS symbols; or (2) that candidate configuration that employs a higher order MCS and that employs the same or fewer additional DMRS symbols; or (3) that candidate configuration that employs a higher level MCS and more additional DMRS symbols and satisfies the following conditions at the same time: the throughput gain that can be incurred in the case of a level increase from the second candidate configured MCS to the first candidate configured MCS is higher than the throughput loss that can be incurred in the case of an increase from the second candidate configured number of additional DMRS symbols to the first candidate configured number of additional DMRS symbols.

Thus, in this example method 200, for the downlink to a given UE, at least one of the number of additional DMRS symbols and the MCS level may be adaptively adjusted according to the mobility speed level, DFO, etc. of the UE, thereby enabling greater throughput gain and/or higher resource utilization, etc.

It should be understood that the order of execution, implementation, etc. of the steps in the example method 200 is not limited to the examples described above.

For example, while step 210 is shown in fig. 2 as preceding step 220, in further examples, step 210 in example method 200 may also be performed after step 220, or may also be performed in parallel with step 220.

For example, in various embodiments, the determination and processing of the candidate configurations may be to determine all candidate configurations in step 230, check whether there is a candidate configuration that meets the conditions in step 240, and then select the optimal or suboptimal candidate configuration to replace the current configuration; alternatively, a candidate configuration may be determined in step 230, checked in step 240 for compliance, and if so, the current configuration may be replaced with the candidate configuration and used as a new current configuration, and then the steps of exemplary method 200 may be repeated until no better candidate configuration is found; it is also possible to determine a candidate configuration in step 230 and check whether the candidate configuration is eligible, then replace the current configuration with the candidate configuration in step 240 if eligible, and then repeat the various steps in the example method 200 in an attempt to find a better candidate configuration; alternatively, a plurality of candidate configurations may be determined in step 230, and a candidate configuration meeting the condition is selected from the plurality of candidate configurations, and then a candidate configuration is further selected, and then the current configuration is replaced with the candidate configuration selected in step 230 in step 240; and so on.

In addition, in different embodiments, when determining candidate configurations that satisfy the condition, referring to the curve set of "BLER versus SINR relationship" for all MCS levels illustrated in fig. 4, for a given BLER target and current configuration, a "greedy" manner may be adopted to search candidate configurations that satisfy the condition from the rightmost curve to the left, or to search candidate configurations that satisfy the condition and are better "gradually" from the left to the right.

In table 1 below, one possible implementation of the example method 200 is shown in pseudo-code. It should be appreciated that the implementation and details of the example method 200 are not limited to the procedures and details shown in pseudo code in table 1, and that other adjustment amounts may be used in the decision conditions, other loop orders, other loop termination conditions, and other step sizes may be used, for example.

Table 1

For example, for the case in fig. 1, unlike the case where the same number of additional DMRS symbols are configured for the downlinks of all UEs in the cell in a static configuration manner, in the exemplary method 200 of the present disclosure, for the

UEs

120, 130, 140, and 150 entering the small region 100, the serving base station may configure different numbers of additional DMRS symbols for the downlinks to the UEs, respectively, and may also simultaneously adjust the MCS levels used by the UEs in the downlinks when performing the adaptive adjustment of the number of additional DMRS symbols for a certain UE, as needed.

For example, for a UE 150 with a high mobile speed level or DFO, a typical configuration of 3 additional DMRS symbols may be initially made according to the O & M setting, and then the current configuration may be further adjusted according to the actual SINR level of the downlink of the UE 150, thereby allowing fewer (e.g., 2, 1, or even 0) additional DMRS symbols and/or higher level MCS to be used.

For example, for a downlink of a UE 120 that may be slow moving or a UE140 that has better channel conditions, fewer (e.g., 1) additional DMRS symbols may be configured, or even no additional DMRS symbols may be configured (disabled), and then the current configuration may be further adjusted by the example method 200 to allow fewer (e.g., 0) additional DMRS symbols and/or higher level MCSs to be used. Thereby, a dynamic adaptive configuration of the downlink to the UE can be achieved.

As described above, in the method of the embodiment of the present disclosure, different numbers of downlink additional DMRS symbols may be configured for a given UE according to its own characteristics (e.g., a mobility speed level, a DFO level, etc. of the UE); then, at least one of the number of additional DMRS symbols and the MCS level may be further adjusted according to the channel quality from the base station to the UE, thereby allowing further using fewer additional DMRS symbols while keeping the MCS level unchanged, further using a higher level MCS while keeping the number of additional DMRS symbols unchanged, further using fewer additional DMRS symbols and a higher level MCS at the same time, even using a higher level MCS but using more additional DMRS symbols (in this case, the throughput gain due to MCS level boosting is higher than the throughput loss due to using more additional DMRS symbols), and so on. Thus, by the method of the embodiments of the present disclosure, at least one of the number of downlink additional DMRS symbols and the MCS level can be adaptively configured for a specific UE, and thus, for example, a greater throughput gain, a higher resource utilization rate, and the like can be obtained while ensuring that communication quality is not degraded.

Fig. 5 illustrates an example apparatus for configuring the number of symbols of a downlink additional demodulation reference signal from a base station to a designated UE in an embodiment of the present disclosure. For example, the example apparatus 500 may be part of an access network (e.g., a base station).

As shown in fig. 5, the example apparatus 500 may include at least one processor 510 and at least one memory 520, wherein the at least one memory 520 may include computer program code 530, and the at least one memory 520 and the computer program code 530 may be configured to, with the at least one processor 510, cause the example apparatus 500 to perform at least the example method 200 described above.

In some embodiments, the at least one processor 510 in the example apparatus 500 may include, but is not limited to, at least one hardware processor, including at least one microprocessor such as a central processing unit, or may be part of at least one hardware processor and a special purpose processor such as one developed based on field programmable gate arrays or the like. Additionally, the at least one processor 510 may also include at least one other circuit or element not shown in fig. 5.

In some embodiments, the at least one memory 520 in the example apparatus 500 may include various forms of storage media, such as volatile and/or non-volatile memory. Volatile memory may include, but is not limited to, for example, random access memory, cache memory, and the like. Non-volatile memory may include, but is not limited to, read-only memory, hard disk, flash memory, and the like. Additionally, the at least one memory 520 may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or any combination of the foregoing.

Additionally, in some embodiments, the example apparatus 500 may also include at least one other element, circuit, interface, or the like, such as at least one I/O interface, antenna element, or the like.

In some embodiments, the circuits, components, elements, interfaces, etc. (including the aforementioned at least one processor 510 and at least one memory 520) in the example apparatus 500 may be coupled in some via any suitable connection mechanism, e.g., may include but is not limited to a bus, a crossbar, wired and/or wireless links, etc., and the connection means may include but is not limited to electrical connections, magnetic connections, optical connections, electromagnetic connections, etc.

Fig. 6 illustrates another example apparatus for configuring a number of symbols of a downlink additional demodulation reference signal to a designated UE in an embodiment of the present disclosure. For example, the example apparatus 600 may be part of an access network (e.g., a base station).

As shown in fig. 6, an example apparatus 600 may include a first module 610, a second module 620, and a third module 630.

In some embodiments, the first module 610 may be configured to determine a current configuration of the downlink, the current configuration including a current number of additional DMRS symbols and a current level of MCS, to implement step 210 of the example method 200.

In some embodiments, the first module 610 may be configured to determine the current number of the aforementioned currently configured additional DMRS symbols such that the current number of the aforementioned currently configured additional DMRS symbols is less than or equal to (typically equal to) the number of additional DMRS symbols predetermined for the class to which the mobile speed of the aforementioned downlink terminal device belongs. In some embodiments, the first module 610 may be configured to determine the current number of the aforementioned currently-configured additional DMRS symbols such that the current number of the aforementioned currently-configured additional DMRS symbols is less than or equal to (typically equal to) the number of additional DMRS symbols predetermined for the range to which the doppler frequency offset of the aforementioned downlink terminal device belongs.

In some embodiments, the second module 620 may be configured to determine an indicator reflecting the SINR level of the aforementioned downlink, thereby implementing step 220 of the example method 200.

In some embodiments, the second module 620 may be configured to receive, as the indicator, CQI measured and reported by the terminal device in the case where the terminal device in the downlink moves within the cell. In some embodiments, the second module 620 may be configured to receive, as the indicator, the SS-SINR or CSI-SINR associated with the target cell measured and reported by the terminal device in the case of inter-cell handover of the terminal device in the downlink. In some embodiments, the second module 620 may be configured to determine, as the indicator, a ratio of RSRP measured by the terminal device on the target cell to RSRP measured by the terminal device on all detectable cells except the target cell, to a sum of additive white gaussian noise average power of the terminal device, in a case where inter-cell handover occurs to the terminal device on the downlink.

In some embodiments, the third module 630 may be configured to determine at least one candidate configuration of the aforementioned downlink related to the aforementioned current configuration, each candidate configuration comprising less than the aforementioned current number of additional DMRS symbols and/or a MCS higher than the aforementioned current level, and to replace the aforementioned current configuration with the aforementioned first candidate configuration if the aforementioned at least one candidate configuration comprises a first candidate configuration that satisfies a condition related to the aforementioned indicator, thereby implementing

steps

230 and 240 of the example method 200.

It should be understood that the apparatus according to the embodiments of the present disclosure is not limited to the above examples. The various modules in the example apparatus shown may be connected or coupled together in any suitable manner, and the arrows between the modules are only used to indicate the flow of data or signals of interest, but do not indicate that the flow of data or signals between the modules can only be in the direction of the arrows.

In addition to the above-described methods and apparatus, embodiments of the present disclosure may also be a computer program product comprising computer program instructions that, when executed by a processor, cause the processor to perform the steps in the example methods described above.

The computer program product may write program code for carrying out operations for embodiments of the present disclosure in any combination of one or more programming languages, including an object oriented programming language such as Java, C + + or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computing device, partly on the user's device, as a stand-alone software package, partly on the user's computing device and partly on a remote computing device, or entirely on the remote computing device or server.

Furthermore, embodiments of the present disclosure may also be a computer-readable storage medium having stored thereon computer program instructions that, when executed by a processor, cause the processor to perform the steps in the example methods described above.

The computer-readable storage medium may take any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may include, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or a combination of any of the foregoing. More specific examples (a non-exhaustive list) of the readable storage medium include: an electrical connection having one or more wires, a portable disk, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

The basic principles of the present disclosure have been described above in connection with embodiments, but it should be noted that advantages, effects, and the like, mentioned in the present disclosure are only examples and not limitations, and should not be considered as essential to the various embodiments of the present disclosure. Furthermore, the foregoing disclosure of specific details is for the purpose of illustration and description and is not intended to be limiting, since the disclosure is not intended to be limited to the specific details so described.

The block diagrams of devices, apparatuses, systems referred to in this disclosure are only given as illustrative examples and are not intended to require or imply that the connections, arrangements, configurations, etc. must be made in the manner shown in the block diagrams. These devices, apparatuses, devices, systems may be connected, arranged, configured in any manner, as will be appreciated by those skilled in the art. Words such as "including," "comprising," "having," and the like are open-ended words that mean "including, but not limited to," and are used interchangeably therewith. The words "or" and "as used herein mean, and are used interchangeably with, the word" and/or, "unless the context clearly dictates otherwise. The word "such as" is used herein to mean, and is used interchangeably with, the phrase "such as but not limited to".

Additionally, in the apparatus, devices, and methods of the present disclosure, components or steps may be decomposed and/or recombined. These decompositions and/or recombinations are to be considered equivalents of the present disclosure.

The previous description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the scope of the disclosure. Thus, the present disclosure is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

The foregoing description has been presented for purposes of illustration and description, and is not intended to limit embodiments of the disclosure to the form disclosed herein. While a number of example aspects and embodiments have been discussed above, those of skill in the art will recognize certain variations, modifications, alterations, additions and sub-combinations thereof.

Claims

1. A method for configuring the number of symbols of a downlink additional demodulation reference signal, comprising:

determining a current configuration of a downlink, the current configuration including a current number of additional demodulation reference signal symbols and a current level of modulation coding scheme;

determining an indicator reflecting a signal-to-interference-and-noise ratio level of the downlink;

determining at least one candidate configuration of the downlink relative to the current configuration, each candidate configuration comprising less than the current number of additional demodulation reference signal symbols and/or a modulation coding scheme above the current level; and

replacing the current configuration with the first candidate configuration if the at least one candidate configuration includes a first candidate configuration that satisfies a condition related to the metric.

2. The method of claim 1, wherein the condition related to the indicator comprises: the indicator is higher than a sum of a signal to interference and noise ratio required by a candidate configuration to achieve a specified block error rate target and a signal to interference and noise ratio variance due to a change from the current configuration to the candidate configuration, the signal to interference and noise ratio variance being a difference between a signal to interference and noise ratio required by the candidate configuration to achieve the specified block error rate target and a signal to interference and noise ratio required by the current configuration to achieve the specified block error rate target.

3. The method of claim 1, wherein the at least one candidate configuration further comprises a second candidate configuration that satisfies the condition, and the first candidate configuration provides a greater throughput gain than the second candidate configuration.

4. The method of claim 1, wherein the first candidate configuration includes less than the current number of additional demodulation reference signal symbols and a same modulation coding scheme as the current level.

5. The method of claim 4, wherein the at least one candidate configuration further includes a second candidate configuration satisfying the condition, a level of a modulation coding scheme of the first candidate configuration is the same as a level of a modulation coding scheme of the second candidate configuration, and a number of additional demodulation reference signal symbols of the first candidate configuration is less than a number of additional demodulation reference signal symbols of the second candidate configuration.

6. The method of claim 1, wherein a level of a modulation coding scheme of the first candidate configuration is higher than the current level.

7. The method of claim 6, wherein the at least one candidate configuration further includes a second candidate configuration satisfying the condition, a level of a modulation coding scheme of the first candidate configuration is the same as a level of a modulation coding scheme of the second candidate configuration, and a number of additional demodulation reference signal symbols of the first candidate configuration is less than a number of additional demodulation reference signal symbols of the second candidate configuration.

8. The method of claim 6, wherein the at least one candidate configuration further includes a second candidate configuration satisfying the condition, a level of a modulation coding scheme of the first candidate configuration is higher than a level of a modulation coding scheme of the second candidate configuration, and a number of additional demodulation reference signal symbols of the first candidate configuration is less than or equal to a number of additional demodulation reference signal symbols of the second candidate configuration.

9. The method of claim 6, wherein the at least one candidate configuration further includes a second candidate configuration satisfying the condition, a level of a modulation coding scheme of the first candidate configuration is higher than a level of a modulation coding scheme of the second candidate configuration, a number of additional demodulation reference signal symbols of the first candidate configuration is greater than a number of additional demodulation reference signal symbols of the second candidate configuration, and a throughput gain that can be brought if the level of the modulation coding scheme of the second candidate configuration is raised to the level of the modulation coding scheme of the first candidate configuration is higher than a throughput loss that can be brought if the number of additional demodulation reference signal symbols of the second candidate configuration is increased to the number of additional demodulation reference signal symbols of the first candidate configuration.

10. The method according to any of claims 1 to 9, wherein the indicator comprises a channel quality indication measured and reported by the terminal device in case the terminal device of the downlink moves within a cell.

11. The method according to any of claims 1 to 9, wherein the indicator comprises a signal to interference and noise ratio of a synchronization and broadcast signal block or a signal to interference and noise ratio of a channel state information reference signal associated with a target cell measured and reported by the terminal device in case of an inter-cell handover of the terminal device of the downlink.

12. The method according to any of claims 1 to 9, wherein in case of inter-cell handover of the terminal device of the downlink, the indicator comprises a ratio of the reference signal received power measured by the terminal device for a target cell relative to the sum of the reference signal received power measured by the terminal device for all detectable cells other than the target cell and the additive white gaussian noise average power of the terminal device.

13. The method according to any one of claims 1 to 9, wherein the moving speed corresponds to a plurality of consecutive levels, the current number of additional demodulation reference signal symbols of the current configuration is less than or equal to a typical configuration number of additional demodulation reference signal symbols predetermined for a level to which the moving speed of the terminal device of the downlink belongs, the at least one candidate configuration refers to a candidate configuration when there is no change in the level to which the moving speed of the terminal device belongs, and the number of additional demodulation reference signal symbols of the at least one candidate configuration is less than or equal to the aforesaid typical configuration number.

14. The method according to any of claims 1 to 9, wherein the doppler shift corresponds to a plurality of consecutive ranges, the current number of additional demodulation reference signal symbols of the current configuration is smaller than or equal to a typical configuration number of additional demodulation reference signal symbols predetermined for a range to which the doppler shift of the terminal device of the downlink belongs, the at least one candidate configuration refers to a candidate configuration when no change has occurred to the range to which the doppler shift of the terminal device belongs, and the number of additional demodulation reference signal symbols of the at least one candidate configuration is smaller than or equal to the typical configuration number.

15. An apparatus for configuring the number of symbols of a downlink additional demodulation reference signal, comprising:

a first module configured to determine a current configuration of a downlink, the current configuration including a current number of additional demodulation reference signal symbols and a current level of a modulation coding scheme;

a second module configured to determine an indicator reflecting a signal-to-interference-and-noise ratio level of the downlink;

a third module configured to determine at least one candidate configuration of the downlink related to the current configuration, each candidate configuration comprising less than the current number of additional demodulation reference signal symbols and/or a modulation coding scheme higher than the current level, and to replace the current configuration with a first candidate configuration if the at least one candidate configuration comprises the first candidate configuration satisfying a condition related to the indicator.

16. The apparatus of claim 15, wherein the condition related to the metric comprises: the indicator is higher than a sum of a signal to interference and noise ratio required by a candidate configuration to achieve a specified block error rate target and a signal to interference and noise ratio variance due to a change from the current configuration to the candidate configuration, the signal to interference and noise ratio variance being a difference between a signal to interference and noise ratio required by the candidate configuration to achieve the specified block error rate target and a signal to interference and noise ratio required by the current configuration to achieve the specified block error rate target.

17. The apparatus of claim 15, wherein the at least one candidate configuration further comprises a second candidate configuration that satisfies the condition, and the first candidate configuration provides a greater throughput gain than the second candidate configuration.

18. The apparatus of claim 15, wherein the first candidate configuration comprises less than the current number of additional demodulation reference signal symbols and a same modulation coding scheme as the current level.

19. The apparatus of claim 18, wherein the at least one candidate configuration further comprises a second candidate configuration satisfying the condition, a level of a modulation and coding scheme of the first candidate configuration is the same as a level of a modulation and coding scheme of the second candidate configuration, and a number of additional demodulation reference signal symbols of the first candidate configuration is less than a number of additional demodulation reference signal symbols of the second candidate configuration.

20. The apparatus of claim 15, wherein a level of a modulation coding scheme of the first candidate configuration is higher than the current level.

21. The apparatus of claim 20, wherein the at least one candidate configuration further comprises a second candidate configuration satisfying the condition, a level of a modulation and coding scheme of the first candidate configuration is the same as a level of a modulation and coding scheme of the second candidate configuration, and a number of additional demodulation reference signal symbols of the first candidate configuration is less than a number of additional demodulation reference signal symbols of the second candidate configuration.

22. The apparatus of claim 20, wherein the at least one candidate configuration further comprises a second candidate configuration satisfying the condition, a level of a modulation and coding scheme of the first candidate configuration is higher than a level of a modulation and coding scheme of the second candidate configuration, and a number of additional demodulation reference signal symbols of the first candidate configuration is less than or equal to a number of additional demodulation reference signal symbols of the second candidate configuration.

23. The apparatus of claim 20, wherein the at least one candidate configuration further comprises a second candidate configuration satisfying the condition, a level of a modulation coding scheme of the first candidate configuration is higher than a level of a modulation coding scheme of the second candidate configuration, a number of additional demodulation reference signal symbols of the first candidate configuration is greater than a number of additional demodulation reference signal symbols of the second candidate configuration, and a throughput gain that can be incurred if the level of the modulation coding scheme of the second candidate configuration is raised to the level of the modulation coding scheme of the first candidate configuration is higher than a throughput loss that can be incurred if the number of additional demodulation reference signal symbols of the second candidate configuration is increased to the number of additional demodulation reference signal symbols of the first candidate configuration.

24. The apparatus of any of claims 15 to 23, wherein the second module is configured to receive, as the indicator, a channel quality indication measured and reported by a terminal device of the downlink if the terminal device moves within a cell.

25. The apparatus according to any of claims 15 to 23, wherein the second module is configured to receive, as the indicator, a signal-to-interference-and-noise ratio of a synchronization and broadcast signal block associated with a target cell or a signal-to-interference-and-noise ratio of a channel state information reference signal measured and reported by a terminal device of the downlink in case of an inter-cell handover of the terminal device.

26. The apparatus of any one of claims 15 to 23, wherein the second module is configured to determine, as the indicator, a ratio of a reference signal received power measured by the terminal device for a target cell with respect to a sum of reference signal received powers measured by the terminal device for all detectable cells other than the target cell and a sum of additive white gaussian noise average powers of the terminal device, in case of an inter-cell handover of the terminal device on the downlink.

27. The apparatus according to any one of claims 15 to 23, wherein the moving speed corresponds to a plurality of consecutive levels, and the first module is configured to configure the currently configured current number of additional demodulation reference signal symbols to be less than or equal to a typical configured number of additional demodulation reference signal symbols predetermined for the level to which the moving speed of the terminal device of the downlink belongs. The at least one candidate configuration determined by the third module is a candidate configuration when the grade to which the moving speed of the terminal equipment belongs is not changed, and the number of the additional demodulation reference signal symbols of the at least one candidate configuration is less than or equal to the typical configuration number.

28. The apparatus of any one of claims 15 to 23, wherein doppler shift corresponds to a plurality of consecutive ranges, and the first module is configured to configure the currently configured current number of additional demodulation reference signal symbols to be less than or equal to a typical configured number of additional demodulation reference signal symbols predetermined for a range to which doppler shift of the downlink terminal device belongs. The at least one candidate configuration determined by the third module is a candidate configuration when the range to which the doppler frequency offset of the terminal device belongs is not changed, and the number of additional demodulation reference signal symbols of the at least one candidate configuration is less than or equal to the number of typical configurations.

29. The apparatus of any of claims 15 to 23, wherein the apparatus is at least part of a base station.

30. An apparatus for configuring the number of symbols of a downlink additional demodulation reference signal, comprising:

at least one processor; and

at least one memory including computer program code, and the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to perform the method of any of claims 1 to 14.

31. A computer-readable storage medium having stored thereon instructions for causing an apparatus to perform the method of any one of claims 1 to 14.