WO2023106979A1

WO2023106979A1 - A method performed in a network node for configuring downlink transmissions to a wireless device in a wireless communications network

Info

Publication number: WO2023106979A1
Application number: PCT/SE2021/051227
Authority: WO
Inventors: Niklas JALDÉN; Henrik Asplund; Svante Bergman
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2021-12-09
Filing date: 2021-12-09
Publication date: 2023-06-15
Anticipated expiration: 2024-06-09

Abstract

A network node (110) for configuring a downlink transmission to a wireless device (101) from the network node in a wireless network, comprising obtaining (202) an estimated CSI-report, CSI_SRS-GoB, which is an estimation of what the CSI would be if a wireless device,would be allocated SRS resources by the network node (110), wherein the CSI_SRS-GoB is based on obtained (201) CSI-reports, CSI_SRS, originating from wireless devices (103) previously allocated SRS-resources by the network node; receiving (203) a codebook-based CSI-report, CSI_GoB, from the wireless device (101); matching (204) the CSI_GoB with CSISRS-GoB; obtaining (205), based on the match, a first and second performance estimate of downlink transmissions, P_GoB and P_reci, based on CSI_GoB and CSI_SRS-GoB, and CSI_SRS respectively; comparing (207), P_GoB and P_reci; and configuring (209) the downlink transmission based on comparison (207). A method performed by the network node, a computer program product and a carrier are also provided.

Description

A METHOD PERFORMED IN A NETWORK NODE FOR CONFIGURING DOWNLINK TRANSMISSIONS TO A WIRELESS DEVICE IN A WIRELESS COMMUNICATIONS NETWORK

TECHNICAL FIELD

The present disclosure relates to configuration of downlink transmissions to a wireless device in a wireless communications network. In particular, but not exclusively, the disclosed technology relates to a network node and a method therein for configuration of downlink transmissions to a wireless device in a wireless communications network.

BACKGROUND

To improve coverage and capacity of today's cellular systems, it is becoming more common to use advanced antenna systems, AAS. The gains of an AAS, namely diversity, multiplexing as well as beamforming, depends on how well the transmitting antenna system knows the spatial nature of the channel, often referred to as Channel State Information, CSI, and hence its ability to direct the energy to the target users, and how well it avoids emitting energy to the interfered users.

One common technique for obtaining channel state information in a multi antenna system is the use of standardized codebooks. For such systems, the base stations, BS, transmit a training sequence that the User Equipment's, wireless devices, listen to in order to derive a good option for a downlink, DL, precoder that it signals back to the BS. To keep the signaling overhead low the codebooks contain a limited set of combinations of DL precoding options. Standardized codebooks typically provide a good balance of uplink, UL, signaling overhead in relation to DL single user beamforming gain, and hence beamforming throughput gain. From theory, it is known that linear phase front precoders are optimal in no angular spread scenarios or asymptotically low Signal to Noise Ratio, SNR, regions. Standardized codebooks are examples of these linear phase front precoders with a limited resolution in angular pointing directions.

Another option for obtaining channel information is to let the wireless device send training sequences, Sounding Reference Signals, SRS, to the BS, such that the BS can estimate the UL channel, and then by utilizing that wireless channels are reciprocal, the UL estimates can be used for DL precoding. SRS based channel information is typically well suited for time division duplexing, TDD, systems where the UL and DL occupy the same bands. The SRS based channel state information method typically provides richer information of the actual channel condition and hence better suited for higher order MIMO, multiple-input and multiple-output, transmissions and multi-user-MIMO, MU -Ml MO. However, as the CSI acquisition is based on UL sounding it is dependent on the UL power and may therefore not be optimal in poor coverage situations.

As there are advantages and disadvantages with both CSI acquisition methods described above, it is expected that future communication systems will utilize both codebook as well as reciprocity-based beamforming.

A problem with the solutions of the prior art is how and/or when to utilize codebookbased and/or SRS based CSI acquisition methods. The SRS resources is a limited resource and can therefore not be allocated to wireless devices that would not benefit from said resource. Further, as the SRS resources needed for a user to provide CSI is limited, it is important for a well working AAS system to allocate these resources to wireless devices that benefit from using such. In today's systems there are no methods for assessing if a wireless device would benefit from SRS based CSI acquisition besides trial and error.

There is thus a need for improved methods for automated CSI mode selection.

SUMMARY

It is an object of the present disclosure to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages in the prior art and solve at least the above mentioned problem.

According to a first aspect there is provided a method performed in a network node for configuring a downlink, DL, transmission to a wireless device from the network node in a wireless communications network, the method comprising: obtaining a CSI report, CSISRS-GOB, which is an estimation of what the CSI would be if a wireless device, not currently allocated SRS resources, would be allocated SRS resources by the network node, wherein the CSISRS-GOB is based on at least one CSI report, CSISRS, originating from wireless devices previously allocated SRS resources by the network node; obtaining information indicating a codebook-based CSI report, CSIGOB, from the wireless device; matching CSIGOB with CSISRS-GOB; obtaining, based on the matching, a first performance estimate, PGOB, of DL transmissions towards the wireless device based on CSIGOB and CSISRS-GOB and a second performance estimate, Preci, of DL transmissions towards the wireless device based on at least one CSISRS; comparing the PGOB with the Preci; and configuring the DL transmission to the wireless device from the network node based on the comparing.

According to a second aspect of embodiments herein, a network node for configuring a downlink, DL, transmission to a wireless device from the network node in a wireless communications network is configured to obtain a CSI report, CSISRS-GOB, which is an estimation of what the CSI would be if a wireless device, not currently allocated SRS resources, would be allocated SRS resources by the network node, wherein the CSISRS-GOB is based on at least one CSI report, CSISRS, originating from wireless devices previously allocated SRS resources by the network node; obtaining information indicating a codebook-based CSI report, CSIGOB, from the wireless device; match, CSIGOB with CSISRS-GOB; obtain, based on the matching, a first performance estimate, PGOB, of DL transmissions towards the wireless device based on CSIGOB and CSISRS-GOB and a second performance estimate, Preci, of DL transmissions towards the wireless device based on at least one CSISRS; compare the PGOB with the P_reci; and configure, the DL transmission to the wireless device from the network node based on the compared PGOB and Preci.

By having the method in the network node it is possible to provide an indication whether or not a wireless device would benefit from using reciprocity based beamforming over codebook.

According to a third aspect of embodiments herein, a computer program is also provided configured to perform the method described above. Further, according to a fourth aspect of the embodiments herein, carriers are also provided configured to carry the computer programs configured for performing the method described above

Hence, allocation of resources in the wireless communications network is improved. The present disclosure will become apparent from the detailed description given below. The detailed description and specific examples disclose preferred embodiments of the disclosure by way of illustration only. Those skilled in the art understand from guidance in the detailed description that changes and modifications may be made within the scope of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects, as well as additional objects, features and advantages of the present disclosure, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of example embodiments of the present disclosure, when taken in conjunction with the accompanying drawings.

Some embodiments of the disclosed technology are described below with reference to the accompanying drawings which are by way of example only and in which:

Fig. la schematically illustrates a network node in a wireless network performing network configuration according to some embodiments of the disclosed technology.

Fig. lb is a signalling diagram illustrating embodiments of a network node, performing network configuration according to some embodiments of the disclosed technology.

Fig. 2 is a flowchart depicting embodiments of a method in a network node in a wireless network performing network configuration according to some embodiments of the disclosed technology.

Fig. 3 is a block diagram depicting embodiments of a network node.

DETAILED DESCRIPTION

The figures are schematic and simplified for clarity, and they merely show details which are essential to the understanding of the embodiments presented herein, while other details have been left out. Throughout, the same reference numerals are used for identical or corresponding parts or steps.

TERMINOLOGY The term wireless devices may refer to any type of wireless device or User Equipment, UE, communicating with a network node in a cellular, mobile or radio communication network or system. Examples of such wireless devices are loT devices, mobile phones, cellular phones, Personal Digital Assistants (PDAs), smart phones, tablets, sensors equipped with a UE, Laptop Mounted Equipment (LME) (e.g. USB), Laptop Embedded Equipments (LEEs), Machine Type Communication (MTC) devices, or Machine to Machine (M2M) device, Customer Premises Equipment (CPE), wireless device capable of machine to machine (M2M) communication, Vehicle-to-Vehicle, V2V, wireless device, or V2x wireless devices, etc. It should be noted that the wireless devices, may be have a single antenna or multiple antennas, i.e. more than one antenna, in order to support Single User MIMO, SU-MIMO, or Multi-User MIMO, MU-MIMO, transmissions.

For the sake of describing the embodiments herein, the wireless device 101, 103 may be a wireless device, such as, a cell phone device.

The terms SRS based CSI acquisition, SRS based channel information, SRS resources, SRS based channel information, SRS based channel state information, and SRS channel information are used interchangeably.

The terms Codebook based CSI acquisition, codebook based transmission, codebook resources, codebook based beamforming, codebook CSI, and Grid-of-Beams (GoB), beamforming are used interchangeably.

The term CSIGOB, or sometime referred to as CSIGOB report, is the CSI-report the network node receives from the wireless device in codebook-based CSI operation according to the background art

The term CSISRS, or sometime referred to as CSISRS report, is the CSI the network node derives from an uplink SRS transmission according to the background art

The term CSISRS-GOB, or sometime referred to as CSISRS-GOB report, is a CSI where the network node determines an estimate of the CSIGOB report, i.e., an expected CSIGOB based on the more detailed information available in the CSISRS report. In other words, the CSISRS-GOB is an estimation of what the CSI would be if a wireless device, not currently allocated SRS resources, would be allocated SRS resources. The functionality of the CSISRS-GOB is mapping between the CSI GoB and the CSI SRS-

The term second performance estimate, refers to expected downlink performance when data is precoded based on SRS channel information and is denoted Preci.

The term first performance estimate refers to whereas performance when data is precoded based on codebook CSI and is denoted PGOB.

Fig. la illustrates a simplified architecture of a wireless communications network 100. For the sake of the embodiments herein, the wireless communications network 100 is described here in Fig. 1 as an LTE-based radio communications network, but may also employ technology of any one of 5G NR (New Radio), Long Term Evolution (LTE), LTE-Advanced, Wideband Code Division Multiple Access (WCDMA), Global System for Mobile communications/Enhanced Data rate for GSM Evolution (GSM/EDGE), Worldwide Interoperability for Microwave Access (WiMax), Ultra Mobile Broadband (UMB) or GSM, or any other similar network or system. The wireless communication network 10 may also be an Ultra Dense Network, UDN, which e.g. may transmit on millimetre-waves (mmW). Furthermore, in different embodiments, the wireless communications system network 100 may comprise any number of wired or wireless networks, any number of wireless devices, any number of network nodes, and/or any other components or systems that may facilitate or participate in the communication of data and/or signals over radio links in the wireless communications network 100.

As shown in Fig. la the wireless communication network 100 comprises a network node 110 configured to configuring a downlink, DL, transmission to a wireless device 101. The network node 110 has access to a database 112 comprising historical SRS-reports and codebook-based CSI-data, obtained from a plurality of wireless devices 103 historically allocated with SRS-based CSI acquisition, as well as standardized codebook-based CSI acquisition. Method 200 (further described in detail in relation to Fig.2) aim to determine whether or not the wireless device 101, currently allocated with codebook based transmission, would benefit from using SRS resources instead of codebook-based transmission.

Fig. lb illustrates a signalling diagram of the wireless communication network 100 shown in Fig. la.

As illustrated in the left part of Fig. lb. The network node 110 obtain SRS-based CSI acquisition-data from a plurality of wireless devices 103 previously allocated with SRS-based CSI acquisition. The network node 110 stores the obtained data in the database 112.

In some embodiments, the network node 110 may also obtain codebook-based CSI- data from a plurality of wireless devices 103 previously allocated with standardized codebookbased CSI acquisition. The network node 110 stores the obtained data in the database 112.

The codebook-based CSI-data is gathered as follow: The network node 110 transmits (103-i) a training sequence to the wireless device 103. The wireless device 103 derives (103-ii) a good option for a DL precoder, which is transmitted (103-iii) to the network node 110. The CSI-report which the network node 110 receives from the wireless device 103, denoted CSIGOB in this application, may be stored (103-iv) in the database 112. For ease of reading, it can be assumed that the CSIGOB is stored in the database 112, unless otherwise is stated.

The SRS-based CSI acquisition-data is gathered as follow: The wireless devices 103 sends (103-v) a training sequences, Sounding Reference Signals, SRS, to the network node 110. The network node 110 estimates (103-vi) the UL channel, and then by utilizing (103-vii) that the wireless channels are reciprocal, the UL estimate is used for deriving downlink, DL, precoding. When the network node 110 has derived the CSI from the uplink SRS transmission, denoted CSISRS, the CSISRS, and/or data related to the CSISRS, e.g., a covariance information is stored (103-viii) in the database 112.

As illustrated in the right part of Fig. lb, the wireless device 101 and the network node 110 interact as follow. The network node 110 transmits (101-i) a training sequence that the wireless device 101 receives. The wireless device 101 derives (101-ii) a good option for a DL precoder, which is transmitted (101-iii) to the network node 110. The CSI-report which the network node 110 receives from the wireless device 101, denoted CSIGOB in this application, may be stored in the database 112. For ease of reading, it can be assumed that the CSIGOB is stored (101-v) in the database 112, unless otherwise is stated.

In one embodiment, the network node 110 obtains (101-iv) information indicating a codebook-based report, e.g., an estimate of the CSIGOB report from reciprocity of an early uplink transmissions, e.g., the random access, RACH). This way, the network node 110 does not need to obtain the actual CSIGOB report.

As stated above, the network node 110 in the wireless communication network 100 gathers historical data in the database 112. Thereby, the database 112 comprises a historical data metric for when SRS resources were used, together with the CSIGOB reports. The Historical data metric comprises historical performance metrics and/or other data from which performance can be determined. The method 200 further disclosed in relation to Fig.2 describes how these stored historical measurement can be requested (112-i) and obtained (112-ii) by the network node 110, and thereby used to determine if a wireless device 101 would benefit from using SRS resources or codebook.

Fig. 2 is a flowchart depicting embodiments of a method 200 in a network node 110 in a wireless communication network 100 performing network configuration according to some embodiments of the disclosed technology.

The first aspect of this disclosure shows a method 200 performed in a network node 110 for configuring a downlink, DL, transmission to a wireless device 101 from the network node 110 in a wireless communications network 100. The method 200 comprises the following steps. Obtaining 202 a CSI report, CSISRS-GOB, which is an estimation of what the CSI would be if a wireless device, not currently allocated SRS resources, would would have been allocated with SRS resources by the network node 110. As an example, the PMI is derived as the direction where the majority of the received signal power come from. From extensive log comparisons, the strongest direction of the wide-band average angular direction coincides with the best PMI report form the wireless devices in a majority of the measured locations. The CSISRS-GOB is based on at least one previously obtained 201 CSI report, CSISRS, which originates from a plurality of wireless devices 103 previously allocated SRS resources by the network node 110. The method is also obtaining 203 information indicating a codebook-based CSI report, CSIGOB, from the wireless device 101. The CSIGOB is a codebook-based CSI report, or an estimate of a codebook-based CSI report. The estimate of a codebook-based CSI report is estimated from reciprocity of early uplink, UL, transmissions. The estimation of the CSIGOB is based on a rough estimate of a Precoding Matric Indicator, PMI, direction, for example extracted from Random Access Channel, RACH, transmission.

The method is also matching 204 the CSIGOB with CSISRS-GOB. The matching 204 aims to match samples with the same or similar CSI-indicators, e.g., PMI, Rl and/or CQI from the wireless device 101 and the wireless devices 103. In other words, the CSIGOB is compared with the plurality of CSISRS-GOB. The matching 204 between the obtained CSIGOB from wireless device 101 and the CSISRS-GOB is performed in order to determine what information to obtain from the database 112.

The method 200 proceeds by obtaining 205, based on the matches from the matching 204 a first performance estimate, PGOB, and a second performance estimate, Preci, of DL transmissions towards the wireless device 101. The PGOB towards the wireless device 101 is based on codebook-based CSI reports, CSIGOB, and the CSISRS-GOB; and the Preci of DL transmissions towards the wireless device 101 is based on the SRS-based CSI-reports, CSISRS. The method is then comparing 207 the obtained PGOB, and Preci. After the comparison 207 is performed, the method 200 has determined which of the SRS-based CSI or codebook-based CSI the wireless device 101 would benefit from. Finally, the method configuring 209 the DL transmission to the wireless device 101 from the network node 110 based on the comparison 207 of the PcoB and Preci.

In some embodiments, the configuring 209 comprises configuring the wireless device 110 with SRS resources if Preci is greater than PGOB.

In some embodiments, determining 202 the CSISRS-GOB, is based on channel information and/or estimations of said channel information, which are obtained from the CSISRS. For example, the determining 202 can carried out by utilizing the channel information H, comprised in the CSISRS, and the precoding matric w.

One example of how determining 202 the CSISRS-GOB is by utilizing the equation below. The equation determines the w out of a set of all w in a given codebook that maximizes the DL received power.

arg max | \Hw\ | ² w

In some embodiments, the method 200 further comprises obtaining 201 the CSISRS, which originates from wireless devices 103 previously allocated SRS resources by the network node 110, based on the assumption that the uplink, UL, channel is reciprocal with the downlink, DL channel.

In some embodiments, the method 200 further comprises storing 206 in a database 112, the CSI SRS GOB, and the PGOB and the Preci, and/or Spatial Channel Information, wherein the Spatial Channel Information is the channel H, or an estimate of the channel H, or the covariance information R. In some embodiments, the complete CSISRS is stored in the database 112 instead of parts the data related to the CSISRS, e.g., a covariance information

By storing the CSISRS-GOB, historical SRS transmissions, CSISRS, and codebook-based CSI, the database 112 can be used as a source which can provide indications if a wireless device would benefit from using SRS-based CSI over codebook-based CSI.

The stored CSISRS-GOB can be used as an index in the database. For example, each CSISRS- GOB comprises information of corresponding CSISRS.

Further, storing the PGOB and the Preci, allows the network node 110 to reuse the measurements and thereby obtain a faster and a more efficient method. However, if desirable, the PGOB and/or the Preci can be recalculated.

In some embodiments, the matching 204 of CSIGOB with CSISRS-GOB further comprises that the CSISRS-GOB comprises historically experienced CSI obtained from the database 112. This means that the method 200 obtains a plurality of CSISRS-GOB, which are calculated in advance, i.e., the plurality of CSISRS-GOB define a set of historical estimates of CSIGOB. Thereby, the CSIGOB originating from the wireless device 101, can be compared to a set of historically estimated CSISRS-GOB:S. Put differently they can be matched, with a plurality of historical estimations of CSIGOB:S. This allows the method 200 to improve the matching process, which will affect the proceeding step of comparing 207 the PGOB and the Preci and make the comparison of the PGOB and the P_reci more reliable.

In some embodiments, the matching 204 of the CSIGOB with the CSISRS-GOB, is based on Precoding Matrix Indicator, PMI; Rank Indication, Rl, and/or Channel Quality Indicator, CQL For example, the matching 204 may be performed by comparing CSI reported by wireless device 101 with SRS estimated PMI.

In some embodiments, obtaining 205 PGOB, and P_reCi further comprises estimating 205a PGOB, based on channel state information, CSI, retrieved from the database 112, and Preci, based on channel state information, CSI, retrieved from the database 112. In other words, PGOB, and Preci can be estimated by obtain essential data stored in the database 112.

In some embodiments, obtaining 205 further comprises retrieving 205b, from the database 112, historically experienced performance PGOB and Preci which relates to the performance of the wireless devices 103 when using SRS resources and codebook resources. For example, the PGOB as well as the CSISRS on which Preci is based on, may be stored in the database 112. The estimated Preci and CSISRS can then be obtained from the database 112.

In some embodiments, comparing 207 further comprises comparing 207a the difference between the PGOB and the Preci to a predetermined threshold value a. The threshold value a is designed to provide a desirable ratio of SRS-based CSI and codebook-based CSI in the wireless communication network 100. In inter words, the threshold value a may be set to adjust the performance estimate needed in order to be allocated SRS resources.

In some embodiments, comparing 207 further comprises comparing 207b the different of the PGOB and the Preci to a predetermined tuning factor R. In other words, the Preci may be compared to R * PGOB. This enables to adjust the overall usage of SRS based CSI in relation to codebook based CSI configurations to a target level.

In some embodiments, the tuning factor R, is an individual tuning factor ft for different groups of SRS reports. For example, the group of wireless devices 103 may be clustered into smaller groups having different tuning factors ft for each of the SRS report groups types. This further improves the flexibility to adjust the overall usage of SRS based CSI in relation to codebook based CSI configurations.

In some embodiments, the comparing 207 further comprises updating 207c the tuning factor R based on complete SRS report, or long term average of the SRS report, and/or the use of combined information of relative values of PGOB and PGOB together with acknowledgment, ACK, and negative-acknowledgment, NACK, information from the wireless device 101. For example, the tuning factor may be updated by considering the relative values of the performance, e.g., to tune that the system get a 50% usage of each configuration. However, as the performance of both configurations may be determined from knowing channels state information, CSI, the relative tuning factor may be determined form these without going through the performance.

In some embodiments, the threshold value a is the same value as the tuning factor R.

The tuning factor R, allows the method 200 to adjust the balance of the resources in the wireless communication system. The ratio of the tuning factor R may be adjusted for different scenarios, e.g., maximizing throughput or optimizing energy consumption.

In some embodiments, the configuring 209 of DL transmission further comprises allocating SRS resources based on the load on the wireless communications network 100. This could be the case when there is no risk that the SRS resources could become limited, and the performance criteria may be ignored. For example, if it is determined that a wireless device will benefit from using SRS-based CSI over codebook-based CSI, and there are SRS resources available, the wireless device may be configured with SRS-based CSI without further ado. In some embodiments, the method also comprises updating 210 the obtained PGOB and/or Preci, based on information of the used bitrate, acknowledgment, ACK, and/or negativeacknowledgment, NACK.

In some embodiments, the network node 110 is a radio base station.

To perform the method steps in a network node 110 arrange to configure a DL transmission to a wireless device 101 from the network node 110, the network node 110 may comprise the following arrangement depicted in Fig 3. Fig 3 shows a schematic block diagram of embodiments of a network node 110. The embodiments of the network node 110 described herein may be considered as independent embodiments or may be considered in any combination with each other to describe non-limiting examples of the example embodiments described herein. It should also be noted that, although not shown in Fig. 3, that known conventional features of a network node 110, such as, for example, at least one antenna and a power source, e.g. a battery or main connection, may be assumed to be comprised in the network node 110 but is not shown or described any further in regards to Fig. 3.

The network node 110 may comprise processing circuitry 320 and a memory 323. The processing circuitry 320 may also comprise a receiving module 321 and a transmitting module 322. The receiving module 321 and the transmitting module 322 may comprise Radio Frequency, RF, circuitry and baseband processing circuitry capable of transmitting and receiving a radio signal in the wireless communications network 100. The receiving module 321 and the transmitting module 322 may also form part of a single transceiver. It should also be noted that some or all of the functionality described in the embodiments above as being performed by the network node 110 may be provided by the processing circuitry 320 executing instructions stored on a computer-readable medium, such as the memory 323 shown in Fig. 3. Alternative embodiments of the network node 110 may comprise additional components, such as, for example, an obtaining module 302, receiving module 303, matching module 304, obtaining module 305, comparing module 307, configuring module 309 responsible for providing its functionality to support the embodiments described herein. The network node 110 or processing circuitry 320 is configured to, or may comprise the obtaining module 302 configured to obtaining a CSI report, CSISRS-GOB; receiving module 303 configured to receiving a codebook-based CSI report, CSIGOB; the matching module 304 configured to matching CSIGOB with CSISRS-GOB; the obtaining module 305 for obtaining a first performance estimate, PGOB, and a second performance estimate, Preci; the comparing module 307 for comparing the PGOB and the P_reci; and the configuring module 309 for configuring the DL transmission to the wireless device from the network node 110.

In one example embodiment, the network node 110 or processing circuitry 320 is configured to, or may comprise a updating module 310 configured to, update the obtained PGOB and/or the P_reci based on information of the used bitrate, acknowledgment, ACK, and/or negative-acknowledgment, NACK.

In one example embodiment, the network node 110 or processing circuitry 320 is configured to, or may comprise a obtaining module 301 configured to, obtain the CSISRS, which originates from wireless devices 103 previously served SRS resources by the network node, based on the assumption that the uplink, UL, channel is reciprocal with the downlink, DL, channel.

The description of the example embodiments provided herein have been presented for purposes of illustration. The description is not intended to be exhaustive or to limit example embodiments to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of various alternatives to the provided embodiments. The examples discussed herein were chosen and described in order to explain the principles and the nature of various example embodiments and its practical application to enable one skilled in the art to utilize the example embodiments in various manners and with various modifications as are suited to the particular use contemplated. The features of the embodiments described herein may be combined in all possible combinations of methods, apparatus, modules, systems, and computer program products. It should be appreciated that the example embodiments presented herein may be practiced in any combination with each other. It should be noted that the word "comprising" does not necessarily exclude the presence of other elements or steps than those listed and the words "a" or "an" preceding an element do not exclude the presence of a plurality of such elements. It should further be noted that any reference signs do not limit the scope of the claims, that the example embodiments may be implemented at least in part by means of both hardware and software, and that several "means", "units" or "devices" may be represented by the same item of hardware.

It should also be noted that the various example embodiments described herein are described in the general context of method steps or processes, which may be implemented in one aspect by a computer program product, embodied in a computer-readable medium, including computer-executable instructions, such as program code, executed by computers in networked environments. A computer-readable medium may include removable and nonremovable storage devices including, but not limited to, Read Only Memory (ROM), Random Access Memory (RAM), compact discs (CDs), digital versatile discs (DVD), etc. Generally, program modules may include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Computerexecutable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.

The embodiments herein are not limited to the above described preferred embodiments. Various alternatives, modifications and equivalents may be used. Therefore, the above embodiments should not be construed as limiting.

Claims

CLAIMS A method (200) performed in a network node (110) for configuring a downlink, DL, transmission to a wireless device (101) from the network node (110) in a wireless communications network (100), the method comprising: obtaining (202) a CSI report, CSISRS-GOB, which is an estimation of what the CSI would be if a wireless device, not currently allocated SRS resources, would be allocated SRS resources by the network node (110), wherein the CSISRS-GOB is based on at least one CSI report, CSISRS, originating from wireless devices (103) previously allocated SRS resources by the network node (110); obtaining (203) information indicating a codebook-based CSI report, CSIGOB, from the wireless device (101); matching (204) CSIGOB with CSISRS-GOB; obtaining (205), based on the matching (204), a first performance estimate, PGOB, of DL transmissions towards the wireless device (101) based on CSIGOB and a second performance estimate, Preci, of DL transmissions towards the wireless device (101) based on at least one CSISRS; comparing (207) the PGOB with the P_reci; and configuring (209) the DL transmission to the wireless device (101) from the network node (110) based on the comparing (207). The method (200) according to claim 1, wherein the information indicating a codebook-based CSI report, CSIGOB, from the wireless device (101) is: an codebook-based CSI report; or an estimate of a codebook-based CSI report, which is estimated from reciprocity of early uplink, UL, transmissions. The method (200) according to any of preceding claims, wherein the PGOB is further also based on CSIsRS-GoB- The method (200) according to any of preceding claims, wherein the configuring (209) comprising configuring the wireless device 110 with SRS resources if Preci is greater than PGOB. The method (200) according to any of preceding claims, wherein the determining (202) of the CSISRS-GOB, is based on channel information, and/or estimations of said channel information, which are obtained from the at least one CSISRS. The method (200) according to any of preceding claims, further comprising obtaining (201) the CSISRS, which originates from wireless devices (103) previously served SRS resources by the network node (110), based on the assumption that the uplink, UL, channel is reciprocal with the downlink, DL, channel. The method (200) according to any of preceding claims, further comprises storing (206) in a database (112), the CSISRS-GOB, and the PGOB and the Preci and/or Spatial Channel Information, wherein the Spatial Channel Information is the channel H, or an estimate of the channel H, or the covariance information R.. The method (200) according to claim 7, wherein the matching (204) of CSIGOB with CSISRS-GOB further comprises that the CSISRS-GOB comprises historically experienced CSI obtained from the database (112). The method (200) according to any preceding claims, wherein the matching (204) of the CSIGOB with the CSISRS-GOB, is based on:

- Precoding Matrix Indicator, PMI;

- Rank Indication, Rl; and/or

- Channel Quality Indicator, CQL The method (200) according to claims 7-8, wherein obtaining (205) PGOB, and P_reci further comprises estimating (205a)

PGOB, based on channel state information, CSI, retrieved from the database (112), and 18

Preci, based on channel state information, CSI, retrieved from the database (112)

11. The method (200) according to claims 1-9, wherein obtaining (205) PGOB, and P_reCi further comprises retrieving (205b), from the database (112), historically experienced PGOB and P_reci , wherein PGOB relates to the performance of the wireless devices (103) when using codebook resources, and Preci relates to the performance of the wireless devices (103) when using SRS resources.

12. The method (200) according to any of the preceding claims, wherein comparing (207) further comprises comparing (207a) the difference between the PGOB and the Preci to a predetermined threshold value a.

13. The method (200) according to any of the preceding claims, wherein comparing (207) further comprises comparing (207b) the ratio of the PGOB and the Preci to a predetermined tuning factor, R.

14. The method (200) according to claim 13, wherein the tuning factor R, is an individual tuning factor Ri for different groups of SRS reports.

15. The method (200) according to claims 13-14, wherein the comparing (207) further comprises updating (207c) the tuning factor based on complete SRS report, or a long term average of the SRS reports, and/or the use of combined information of relative values of the PGOB and the Preci together with acknowledgment, ACK, and negative-acknowledgment, NACK, information from the wireless device (101).

16. The method (200) according to claims 12 and 13-15, wherein the threshold value a is the same value as the tuning factor R. 19

17. The method (200) according to any preceding claims, wherein the configuring (209) DL transmission further comprising allocating SRS resources based on the load on the wireless communications network (100).

18. The method (200) according to any of preceding claims, further comprises updating (210) the obtained PGOB and/or Preci based on information of the used bitrate, acknowledgment, ACK, and/or negative-acknowledgment, NACK.

19. The method (200) according to any preceding claims, wherein the network node (110) is a radio base station.

20. A network node (110) for configuring a downlink, DL, transmission to a wireless device (101) from the network node (110) in a wireless communications network (100) being configured to: obtain a CSI report, CSISRS-GOB, which is an estimation of what the CSI would be if a wireless device, not currently allocated SRS resources, would be allocated SRS resources by the network node (110), wherein the CSISRS-GOB is based on at least one CSI report, CSISRS, originating from wireless devices (103) previously allocated SRS resources by the network node (110); obtain information indicating a codebook-based CSI report, CSIGOB, from the wireless device (101); match CSIGOB with CSISRS-GOB; obtain, based on the matching (204), a first performance estimate, PGOB, of DL transmissions towards the wireless device (101) based on CSIGOB and a second performance estimate, Preci, of DL transmissions towards the wireless device (101) based on at least one CSISRS; compare the PGOB with the Preci; and configure the DL transmission to the wireless device (101) from the network node (110) based on the comparing (207). 20 The network node (110) according to claim 20, wherein the information indicating a codebook-based CSI report, CSIGOB, from the wireless device (101) is: an codebook-based CSI report; or an estimate of a codebook-based CSI report, which is estimated from reciprocity of early uplink, UL, transmissions. The network node (110) according to any claims 20-21, wherein the PGOB is further also based on CSIsRS-GoB- The network node (110) according to any claims 20-22, wherein the configuring comprising configuring the wireless device 110 with SRS resources if Preci is greater than PGOB. The network node (110) according to any claims 20-23, wherein the determining of the CSISRS- GOB, is based on channel information, and/or estimations of said channel information, which are obtained from the at least one CSISRS. The network node (110) according to any claims 20-24, further configured to obtain the CSISRS, which originates from wireless devices (103) previously served SRS resources by the network node (110), based on the assumption that the uplink, UL, channel is reciprocal with the downlink, DL, channel. The network node (110) according to any claims 20-25, further configured to store in a database (112), the CSISRS-GOB, and the PGOB and the Preci and/or Spatial Channel Information, wherein the Spatial Channel Information is the channel H, or an estimate of the channel H, or the covariance information R.. The network node (110) according to any claims 20-26, wherein the match of CSIGOB with CSISRS-GOB further comprises that the CSISRS-GOB comprises historically experienced CSI obtained from the database (112). 21 The network node (110) according to any claims 20-27, wherein the match of the CSIGOB with the CSISRS-GOB, is based on:

- Precoding Matrix Indicator, PMI;

- Rank Indication, Rl; and/or

- Channel Quality Indicator, CQL The network node (110) according to any claims 26-27, wherein obtain PGOB, and Preci further comprises estimating

PGOB, based on channel state information, CSI, retrieved from the database (112), and

Preci, based on channel state information, CSI, retrieved from the database (112) The network node (110) according to any claims 28-29, wherein obtain PGOB, and P_reci further comprises retrieve, from the database (112), historically experienced PGOB and P_reci , wherein PGOB relates to the performance of the wireless devices (103) when using codebook resources, and Preci relates to the performance of the wireless devices (103) when using SRS resources. The network node (110) according to any claims 20-30, wherein compare further comprises compare the difference between the PGOB and the Preci to a predetermined threshold value a. The network node (110) according to any claims 20-31, wherein compare further comprises compare the ratio of the PGOB and the Preci to a predetermined tuning factor, R. The network node (110) according to claim 32, wherein the tuning factor R, is an individual tuning factor ft for different groups of SRS reports. 22

34. The network node (110) according to any claims 31-32, wherein the compare further comprises update the tuning factor R based on complete SRS report, or a long term average of the SRS reports, and/or the use of combined information of relative values of the PGOB and the Preci together with acknowledgment, ACK, and negative-acknowledgment, NACK, information from the wireless device (101).

35. The network node (110) according to any claims 31 and 32-34, wherein the threshold value a is the same value as the tuning factor R.

36. The network node (110) according to any claims 20-35, wherein the configure the DL transmission further comprising allocate SRS resources based on the load on the wireless communications network (100).

37. The network node (110) according to any claims 20-36, further comprises update the obtained PGOB and/or P_reci based on information of the used bitrate, acknowledgment, ACK, and/or negative-acknowledgment, NACK.

38. The network node (110) according to any claims 20-37, wherein the network node (110) is a radio base station.

39. A computer program comprising program code means for performing the steps of any of claims 1-20 when said program is run on a computer or on processing circuitry in a network node (110).

40. A computer program carrier carrying a computer program according to claim 39, wherein the computer program carrier is one of an electronic signal, optical signal, radio signal, or computer-readable storage medium.