WO2024094310A1 - Approches de transmission mimo - Google Patents

Approches de transmission mimo Download PDF

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Publication number
WO2024094310A1
WO2024094310A1 PCT/EP2022/080813 EP2022080813W WO2024094310A1 WO 2024094310 A1 WO2024094310 A1 WO 2024094310A1 EP 2022080813 W EP2022080813 W EP 2022080813W WO 2024094310 A1 WO2024094310 A1 WO 2024094310A1
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WIPO (PCT)
Prior art keywords
user
downlink
signal quality
uplink channel
quality value
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PCT/EP2022/080813
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English (en)
Inventor
Xueying Hou
Yusheng Liu
Mats ÅHLANDER
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Telefonaktiebolaget Lm Ericsson (Publ)
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Priority to PCT/EP2022/080813 priority Critical patent/WO2024094310A1/fr
Publication of WO2024094310A1 publication Critical patent/WO2024094310A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0452—Multi-user MIMO systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0002—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate
    • H04L1/0003—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate by switching between different modulation schemes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0009—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the channel coding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/20—Arrangements for detecting or preventing errors in the information received using signal quality detector

Definitions

  • the present disclosure relates generally to the field of wireless communication. More particularly, it relates to approaches for multiple-input multiple-output (MIMO) transmission.
  • MIMO multiple-input multiple-output
  • a general problem in relation to wireless communication is how to achieve as high throughput as possible under given channel conditions. This problem is also applicable for multiple-input multiple-output (MIMO) transmission.
  • MIMO multiple-input multiple-output
  • the physical product may comprise one or more parts, such as controlling circuitry in the form of one or more controllers, one or more processors, or the like. It is an object of some embodiments to solve or mitigate, alleviate, or eliminate at least some of the above or other disadvantages.
  • a first aspect is a method for a radio access node.
  • the method is for communicating with a plurality of users by multiple-input multiple-output (MIMO) transmission.
  • the radio access node is configured to receive user feedback, and to use uplink channel estimates for downlink beamforming of the MIMO transmission.
  • the method comprises estimating a user-specific signal quality value, wherein the signal quality value is a signal-to-interference ratio (SIR) value and/or a signal-to-interference-and-noise ratio (SINR) value, and performing or causing downlink MIMO transmission to one or more user of the plurality of users based on respective estimated signal quality value.
  • SIR signal-to-interference ratio
  • SINR signal-to-interference-and-noise ratio
  • Estimating the signal quality value comprises combining a desired power component and a total power component, wherein the desired power component is determined from an extended downlink channel model, wherein the total power component is determined from the extended downlink channel model, and is compensated for uncertainties of the uplink channel estimate and/or estimated disturbances at the user, and wherein the extended downlink channel model is a combination of a downlink beamforming precoder, an estimation of a downlink radio channel, and a receiver model of the one or more user determined based on the user feedback.
  • the estimation of the downlink radio channel comprises a reciprocity version of uplink channel estimates, wherein uplink channel estimates used for the estimation of the downlink radio channel relate to one or more frequency sub-band and/or sub-carrier, which is different than a frequency sub-band and/or sub-carrier related to uplink channel estimates used for the downlink beamforming precoder.
  • uplink channel estimates used for the estimation of the downlink radio channel and uplink channel estimates used for the downlink beamforming precoder relate to different sub-carriers within a sub-carrier group.
  • the receiver model of the one or more user matches a combination of the downlink beamforming precoder and the estimation of the downlink radio channel, as compensated for uncertainties of the uplink channel estimate and/or estimated disturbances at the user.
  • the total power component comprises inter-layer interference power and/or inter-user interference power, as derived from the extended downlink channel model.
  • compensation of the total power component comprises a combination of the receiver model of the one or more user with uncertainties of the uplink channel estimate and/or estimated disturbances at the user.
  • the uncertainties of the uplink channel estimate are determined from the downlink beamforming precoder and a variance relating to the uncertainties of the uplink channel estimates.
  • estimated disturbances at the user comprises inter-user interference caused by using the uplink channel estimates for downlink beamforming.
  • estimated disturbances at the user is determined based on the user feedback.
  • the estimated disturbances at the user is determined from one or more of: a reciprocity version of uplink channel estimates used for downlink beamforming, beamforming indicated by the user feedback, and signal quality value and rank indicated by the user feedback.
  • the estimated disturbances at the user is determined from an effect of a combination of the beamforming indicated by user feedback and the reciprocity version of uplink channel estimates used for downlink beamforming, as biased by the signal quality value and rank indicated by user feedback.
  • estimating the user-specific signal quality value comprises estimating intermediate user-specific signal quality values per sub-carrier group, transforming (for each of a plurality of modulation order hypotheses) each intermediate user-specific signal quality value to a spectrum efficiency value, accumulating (for each of the plurality of modulation order hypotheses) the spectrum efficiency values over a plurality of sub-carrier groups, selecting (based on the accumulated spectrum efficiency values) a modulation order from the plurality of modulation order hypotheses, and transforming the accumulated spectrum efficiency values of the selected modulation order to the estimated user-specific signal quality value.
  • the MIMO transmission comprises using the estimated user-specific signal quality value for controlling transport formal selection of an upcoming transmission occasion.
  • the MIMO transmission comprises using the estimated user-specific signal quality value for link adaptation.
  • using the estimated user-specific signal quality value for link adaptation comprises selecting a modulation and coding scheme (MCS) that is associated with the estimated user-specific signal quality value.
  • MCS modulation and coding scheme
  • the MIMO transmission comprises one or more of: a multi-user (MU) MIMO transmission, and a single-user (SU) MIMO transmission.
  • MU multi-user
  • SU single-user
  • the MU MIMO transmission comprises dynamic MU grouping overtime, or un-dynamic MU grouping.
  • the user feedback comprises one or more of: channel quality information (CQI), precoding matrix index (PMI), and rank indicator (Rl).
  • CQI channel quality information
  • PMI precoding matrix index
  • Rl rank indicator
  • the uplink channel estimates are determined by the radio access node based on one or more user transmission of at least one type of uplink signal.
  • the at least one type of uplink signal comprises sounding reference signal (SRS) and/or demodulation reference signal (DMRS).
  • SRS sounding reference signal
  • DMRS demodulation reference signal
  • a second aspect is a computer program product comprising a non-transitory computer readable medium, having thereon a computer program comprising program instructions.
  • the computer program is loadable into a data processing unit and configured to cause execution of the method according to the first aspect when the computer program is run by the data processing unit.
  • a third aspect is an apparatus for a radio access node configured for communication with a plurality of users by multiple-input multiple-output (MIMO) transmission, wherein the radio access node is configured to receive user feedback, and wherein the radio access node is configured to use uplink channel estimates for downlink beamforming of the MIMO transmission.
  • the apparatus comprises controlling circuitry configured to cause estimation of a user-specific signal quality value, wherein the signal quality value is a signal-to-interference ratio (SIR) value and/or a signal-to-interference-and-noise ratio (SINR) value, and downlink MIMO transmission to one or more user of the plurality of users based on respective estimated signal quality value.
  • SIR signal-to-interference ratio
  • SINR signal-to-interference-and-noise ratio
  • Estimation of the signal quality value comprises combination of a desired power component and a total power component, wherein the desired power component is determined from an extended downlink channel model, wherein the total power component is determined from the extended downlink channel model, and is compensated for uncertainties of the uplink channel estimate and/or estimated disturbances at the user, and wherein the extended downlink channel model is a combination of a downlink beamforming precoder, an estimation of a downlink radio channel, and a receiver model of the one or more user determined based on the user feedback.
  • a fourth aspect is a radio access node comprising the apparatus of the third aspect.
  • a fifth aspect is a server node comprising the apparatus of the third aspect, wherein the server node is configured to control the radio access node.
  • a sixth aspect is a control node comprising the apparatus of the third aspect, wherein the control node is configured to control a plurality of access points of a distributed MIMO system, and wherein the radio access node is one of the access points.
  • any of the above aspects may additionally have features identical with or corresponding to any of the various features as explained above for any of the other aspects.
  • An advantage of some embodiments is that alternative approaches to MIMO transmission are provided.
  • An advantage of some embodiments is that increased throughput is provided compared to other approaches.
  • An advantage of some embodiments is that improved link adaptation is provided compared to other approaches (e.g., selection of a modulation and coding scheme, MCS, that is more appropriate for the communication scenario at hand).
  • MCS modulation and coding scheme
  • An advantage of some embodiments is that a radio access node is enabled to predict downlink SINR for link adaptation in MU-MIMO transmission. This enables the radio access node to select a proper MCS, which matches not only the downlink channel conditions but also the dynamic pairing of multiple UEs, so that the total throughput can be improved compared to other approaches.
  • being more appropriate for a communication scenario may be defined as achieving higher throughput in the communication scenario.
  • throughput may refer to throughput for an individual user and/or to accumulated throughput for two or more users.
  • Figure 1 is a flowchart illustrating example method steps according to some embodiments
  • Figure 2A is a schematic block diagram illustrating example functions according to some embodiments.
  • Figure 2B is a schematic drawing illustrating an example sub-carrier group according to some embodiments.
  • Figure 3 is a schematic block diagram illustrating an example apparatus according to some embodiments.
  • Figures 4A-C are schematic drawings illustrating example communication scenarios according to some embodiments.
  • Figure 5 is a schematic drawing illustrating an example computer readable medium according to some embodiments
  • Figure 6 schematically illustrates a telecommunication network connected via an intermediate network to a host computer
  • Figure 7 is a generalized block diagram of a host computer communicating via a base station with a user equipment over a partially wireless connection;
  • FIGS 8 and 9 are flowcharts illustrating methods implemented in a communication system including a host computer, a base station and a user equipment.
  • the term "user” is meant to encompass a user equipment (UE), as well as any other suitable wireless communication device (e.g., a station - STA - compliant with an IEEE802.il standard, an Internet-of-Things - loT- device, etc.), and the term "radio access node” is meant to encompass a base station (BS; e.g., a gNB), as well as any other suitable wireless communication node (e.g., an access point - AP - compliant with an IEEE802.il standard, an access point of a distributed MIMO system, etc.).
  • BS base station
  • any other suitable wireless communication node e.g., an access point - AP - compliant with an IEEE802.il standard, an access point of a distributed MIMO system, etc.
  • channel may refer to the transfer conditions only (i.e., conditions between transmitter antenna(s) and reception antenna(s)), or may also include the impact of one or more components of the transmitter and/or the impact of one or more components of the receiver.
  • MIMO communication in a wireless communication network is a technique wherein spatial diversity is exploited for using the same time and frequency resource to serve several users simultaneously, or to serve one user with multiple information streams. This is also referred to as spatial multiplexing.
  • MIMO is applied between a gNB and a UE, the gNB and/or the UE are equipped with multiple antennas. Spatial diversity typically enables more efficient utilization of the frequency spectrum compared to other communication techniques.
  • MIMO can reduce inter-cell interference and/or intra-cell interference, which may improve the possibilities for frequency re-use.
  • MIMO layers two or more data streams (MIMO layers) are transmitted over respective (ideally independent) channels that are spatially separated in space.
  • the throughput increases when the number of simultaneously transmitted parallel MIMO layers increases.
  • Single user (SU) MIMO refers to a situation when the spatial layers are utilized for transmission to a single UE and multi user (MU) MIMO refers to a situation when the spatial layers are utilized for transmission to two or more UEs (each UE being associated with one or more of the layers).
  • SU single user
  • MU multi user
  • DL transmission beamforming is a technique where a weighted coherent phase shift is added to each base station antenna element with the effect of creating a concentrated beam of energy from the base station antenna array towards a UE.
  • the phase shifts are often collectively referred to as a pre-coder.
  • beamforming For example, a Minimum Mean Square Estimator (MMSE) criterion or a Singular Value Decomposition (SVD) criterion may be used for computation of beam weights.
  • MMSE Minimum Mean Square Estimator
  • beamforming enables reduction of inter-user interference as well as energy concentration towards each UE, which typically improves throughput.
  • Efficient utilization of spatial channel separation is typically also related to how well the number of MIMO layers are matched to the rank of the channel and/or to how well link adaptation (e.g., selection of modulation and coding scheme - MCS) is performed for the channel. If the selected number of MIMO layers and MCS are not well suited for the selected pre-coder, the throughput will typically not reach the full potential of the channel.
  • the selected pre-coder can support a specific number (e.g., four) MIMO layers with the highest MCS index
  • the gNB transmits a lower number of (e.g., only three) MIMO layers and/or uses a lower MCS index
  • the throughput will be restricted by the conservative selection of the gNB.
  • CSI channel state information
  • the UE(s) may be configured to perform measurements on reference signals (e.g., CSI reference signal - CSI-RS) transmitted by the gNB to determine DL channel estimates, and send user feedback (e.g., in the form of CSI reports) indicating the DL channel estimates to the gNB.
  • reference signals e.g., CSI reference signal - CSI-RS
  • user feedback e.g., in the form of CSI reports
  • the gNB may be configured to perform measurements on reference signals (e.g., sounding reference signal - SRS) transmitted by the UE(s) to determine uplink (UL) channel estimates.
  • reference signals e.g., sounding reference signal - SRS
  • UL channel estimates are used by the gNB for DL beamforming.
  • the DL channel is so similar to the reverse UL channel (possibly except for a power scaling factor) that beamforming based on the UL channel estimates can be applied for DL transmission instead of beamforming based on the DL channel estimates.
  • This may be referred to as reciprocity based beamforming.
  • reciprocity based beamforming is in time division duplex (TDD) systems.
  • the gNB is configured to receive user feedback from UE(s) (e.g., in the form of CSI reports; typically including channel quality information - CQI, precoding matrix index - PM I, and rank indicator - Rl).
  • the gNB is typically configured to use the user feedback for part of the configuration of downlink transmission (e.g., use the CQI for MCS selection, and/or use the Rl for selection of number of MIMO layers).
  • the downlink transmission configuration (e.g., MCS) will typically not be optimal for the beamforming that the gNB applies.
  • OLA outer-loop adjustment
  • OLA approaches are well known and will not be elaborated on further herein. Some problems with OLA approaches is that they converge relatively slowly, that they are typically unable to follow rapidly varying channel conditions and/or dynamic MU pairing/grouping, and that they are unsuitable for scenarios with sporadic traffic.
  • the reciprocity based beamforming may be less than optimal. Furthermore, it is a problem that MCS selection does not match the applied beamforming when it is based on an assumption of codebook based transmission, while the gNB applies reciprocity based beamforming.
  • Some embodiments address these and/or other problems by providing approaches in which the gNB (or another node) estimates a user-specific signal quality value (e.g., a signal-to- interference ratio, SIR, value and/or a signal-to-interference-and-noise ratio, SINR, value), which may then be used for the downlink MIMO transmission (e.g., for selection of MCS).
  • a user-specific signal quality value e.g., a signal-to- interference ratio, SIR, value and/ora signal-to-interference-and-noise ratio, SINR, value
  • SINR signal-to-interference-and-noise ratio
  • the suggested approaches may provide faster convergence, and/or ability to follow rapidly varying conditions (e.g., of the channel and/or MU grouping), and/or suitability for scenarios with sporadic traffic.
  • the gNB In an ideal scenario, it is typically possible for the gNB to accurately predict the downlink transmission conditions for an upcoming downlink MU-MIMO transmission Such a predication may be based on the downlink beamforming precoder to be applied for the transmission, the downlink radio channel from gNB to UE, the interference plus noise (IpN) as experienced by the UE, and receiver particulars of the UE (e.g., spatial de-multiplexing, equalization, channel estimation, etc.).
  • the prediction may, for example, comprise prediction of UE downlink reception behavior, which may enable the gNB to find an optimal number of layers and/or an optimal MCS for the UE.
  • the downlink beamforming precoder to be applied for the transmission, the downlink radio channel from gNB to UE, the interference plus noise (IpN) as experienced by the UE, and receiver particulars of the UE).
  • IpN interference plus noise
  • the estimated uplink channel will include imperfections such as uplink noise and interference experienced at gNB when performing the uplink channel estimation.
  • the estimated downlink channel derived by reciprocity will not be an accurate estimation of the actual downlink radio channel. This will be referred to as uplink channel estimation error.
  • Using the downlink channel derived by reciprocity might lead to an erroneous estimation (e.g., overestimation) of the signal quality value (e.g., SIR, SINR, etc.), which in turn may lead to a sub-optimal MCS selection.
  • the precoder applied at the gNB may have a coarse granularity (e.g., to save computational complexity).
  • the precoder may be based on sub-band granularity (e.g., sub-carrier group granularity) rather than being based on sub-carrier granularity.
  • a sub-band granularity precoder may be use the channel estimation for one of the sub-carriers in the sub-band for precoder calculation, and apply that precoder for all of the sub-carriers in the sub-band.
  • the precoder is not optimal for all sub-carriers. This situation may also contribute to an erroneous situation (e.g., overestimation) of the signal quality value (e.g., SIR, SINR, etc.), which in turn may lead to a sub-optimal MCS selection.
  • the signal quality value e.g., SIR, SINR, etc.
  • the gNB typically does not have information available regarding the IpN experienced by the UE, nor information regarding UE reception behavior.
  • the gNB may estimate the IpN experienced by the UE based on feedback from UE (e.g., CQI, PMI, Rl) together with the uplink radio channel estimation, and make some assumptions regarding UE reception behavior. Some embodiments provide approaches suitable for these purposes.
  • the gNB uses information gathered (acquired) at the gNB to predict the downlink per-SCG SINR experienced at each UE for MIMO transmission (e.g., MU-MIMO).
  • the acquired information typically includes one or more of: CSI feedback from the UE (user feedback), uplink channel estimation based on SRS (uplink channel estimates), downlink precoder applied by the gNB for beamforming (downlink beamforming precoder), scheduled UEs, number of layers for each scheduled UE, estimation of interference plus noise (IpN) experienced at the UE (estimated disturbances at the user), uplink channel estimation error (uncertainties discrepancies of the uplink channel estimate), and outer loop adjustment.
  • CSI feedback from the UE user feedback
  • uplink channel estimation based on SRS uplink channel estimates
  • downlink precoder applied by the gNB for beamforming downlink beamforming precoder
  • scheduled UEs number of layers for each scheduled UE
  • the SINR estimation can become more accurate. Furthermore, some embodiments suggest application of a frequency shift between the channel used for SINR estimation and the channel used for precoder calculation, which improves the accuracy in scenarios with frequency selective channels.
  • Figure 1 illustrates an example method 100 according to some embodiments.
  • the method 100 is for a radio access node configured to communicate with a plurality of users by multiple-input multiple-output (MIMO) transmission.
  • MIMO multiple-input multiple-output
  • the method 100 may be performed by the radio access node. Alternatively or additionally, the method 100 may be performed by a server node (e.g., a central network node or a cloud server) controlling the radio access node. Yet alternatively or additionally, the method 100 may be performed by a control node configured to control a plurality of access points of a distributed MIMO system.
  • a server node e.g., a central network node or a cloud server
  • control node configured to control a plurality of access points of a distributed MIMO system.
  • the method 100 may be performed by a single node (e.g., a radio access node). Alternatively, the method 100 may be distributedly performed; i.e., two or more nodes (e.g., cloud computing nodes) each performing one or more steps, or part of a step, or the method 100.
  • a single node e.g., a radio access node
  • the method 100 may be distributedly performed; i.e., two or more nodes (e.g., cloud computing nodes) each performing one or more steps, or part of a step, or the method 100.
  • the radio access node is configured to receive user feedback, which is typically indicative of downlink channel estimates.
  • the user feedback may be in the form of channel state information (CSI) reports, and/or the downlink channel estimates may be based on user measurements on channel state information reference signals (CSI-RS) transmitted by the radio access node.
  • CSI-RS channel state information reference signals
  • the user feedback comprises one or more of: channel quality information (CQI), precoding matrix index (PMI), and rank indicator (Rl).
  • CQI channel quality information
  • PMI precoding matrix index
  • Rl rank indicator
  • the user feedback is derived by the corresponding UE under a single-user SU assumption.
  • the radio access node is also configured to use uplink channel estimates for (e.g., reciprocity based) downlink beamforming of the MIMO transmission.
  • uplink channel estimates may be based on radio access node measurements on uplink signals transmitted by the user(s).
  • SRS sounding reference signals
  • the SRS is an uplink only signal.
  • the SRS is transmitted by the user(s) to help the gNB obtain channel state information for each user.
  • uplink signals and/or uplink reference signals may -alternatively or additionally - be used to obtain uplink channel estimates.
  • the Demodulation Reference Signal DMRS
  • DMRS Demodulation Reference Signal
  • the uplink channel estimate based (e.g., reciprocity based) beamforming may be determined by the radio access node (or by another suitable node, such as a server node; e.g., a central network node or a cloud server) based on the uplink channel estimates.
  • the method may comprise acquiring information. In some embodiments, part/all of this information is already available when/where the method 100 is performed.
  • step 110 may comprise acquiring user feedback (e.g., receiving a CSI report), as illustrated by sub-step 112.
  • step 110 may comprise performing - or otherwise acquiring - UL measurements (e.g., SRS measurements), as illustrated by sub-step 114.
  • - UL measurements e.g., SRS measurements
  • step 110 may comprise retrieving the beamforming (BF) setting (i.e., the downlink beamforming precoder), as illustrated by sub-step 116.
  • the BF setting may comprise the BF setting used when the DL measurements were made and/or the BF setting that will be used for the upcoming MIMO transmission.
  • step 110 may comprise estimating disturbances at the user 8 ⁇ , as illustrated by sub-step 117.
  • the estimated disturbances may comprise inter-user interference (experienced at the user) caused by using the uplink channel estimates for downlink beamforming.
  • the estimate of disturbances at the user is determined based on the user feedback.
  • the estimate of disturbances at the user may be determined from one or more of: a reciprocity version of uplink channel estimates used for downlink beamforming H ⁇ coder , beamforming indicated by the user feedback W M/ , and signal quality value S1NR ⁇ B and rank Rl ⁇ b indicated by the user feedback.
  • the estimated disturbances at the user may be determined from an effect of a combination HTM 1 of the beamforming indicated by user feedback and the reciprocity version of uplink channel estimates used for downlink beamforming, as biased by the signal quality value and rank indicated by user feedback.
  • step 110 may comprise determining a variance (and/or other relevant uncertainties/discrepancies) for the uplink channel measurements, as illustrated by sub-step 118.
  • uncertainties of the uplink channel estimate are determined from the downlink beamforming precoder and a variance 8 , srs h t (b,p ⁇ ) relating to the uncertainties of the uplink channel estimates.
  • step 110 may comprise retrieving the current OLA setting, as illustrated by sub-step 119.
  • a user-specific signal quality value (e.g., an SIR value or an SINR value) is estimated.
  • the user-specific signal quality value may be determined based on spectrum efficiency (e.g., throughput) as illustrated by sub-step 140.
  • the signal quality value y u fc (Z) is estimated by combining a desired power component P s ⁇ k (/) and a total power component
  • the desired power component is determined (as illustrated by sub-step 134) from an extended downlink channel model H ⁇ k .
  • the extended downlink channel model is a combination of a downlink beamforming precoder an estimation of a downlink radio channel H s ⁇ k t , and a receiver model V u k of the one or more user determined (as illustrated by sub-step 132) based on the user feedback.
  • the total power component P ⁇ (Z) is also determined (as illustrated by sub-step 136) from the extended downlink channel model H ⁇ k , and is compensated for uncertainties of the uplink channel estimate R ⁇ k and/or estimated disturbances at the user
  • the total power component may comprise inter-layer interference power : )
  • the compensation of the total power component may comprise a combination of the receiver model of the one or more userwith uncertainties of the uplink channel estimate and/or estimated disturbances at the user.
  • sub-steps 132, 134, 136 are typically performed per sub-carrier group.
  • the receiver model of the one or more user matches a combination of the downlink beamforming precoder and the estimation of the downlink radio channel, as compensated for uncertainties of the uplink channel estimate R ⁇ k and/or estimated disturbances at the user
  • the estimation of the downlink radio channel may comprise a reciprocity version of uplink channel estimates, wherein uplink channel estimates used for the estimation of the downlink radio channel relate to one or more frequency sub-band and/or sub-carrier, which is different than a frequency sub-band and/or sub-carrier related to uplink channel estimates used for the downlink beamforming precoder (i.e., implementing a frequency shift; see also Figure 2B).
  • uplink channel estimates used for the estimation of the downlink radio channel and uplink channel estimates used for the downlink beamforming precoder may relate to different sub-carriers within a sub-carrier group.
  • estimating the user-specific signal quality value in step 120 comprises estimating intermediate user-specific signal quality values per sub-carrier group (as illustrated by sub-step 138), and transforming S1NR21CC (for each of a plurality of modulation order hypotheses) each intermediate user-specific signal quality value to a spectrum efficiency value (e.g., throughout).
  • the spectrum efficiency values may be accumulated (for each of the plurality of modulation order hypotheses) over a plurality of sub-carrier groups, a modulation order mod max may be selected from the plurality of modulation order hypotheses (based on the accumulated spectrum efficiency values), and the accumulated spectrum efficiency values of the selected modulation order may be transformed 1CC2S1NR to the estimated user-specific signal quality value (possibly after averaging over layers).
  • step 160 downlink (DL) MIMO transmission to one or more user of the plurality of users is performed (e.g., when the method 100 is performed by a radio access node) or caused (e.g., when the method 100 is performed by a server node or a control node).
  • the DL MIMO transmission to the one or more user is based on the respective estimated signal quality value.
  • the DL MIMO transmission may be a single-user (SU) MIMO transmission or a multi-user (MU) MIMO transmission.
  • DL MIMO transmission may comprise using the estimated signal quality value for controlling the MIMO configuration (e.g., a transport formal selection) of an upcoming transmission occasion, as illustrated by optional sub-step 150.
  • the estimated signal quality value may be used for link adaptation, as illustrated by 152.
  • the link adaptation may comprise selecting a modulation and coding scheme (MCS) that is associated with the estimated signal quality value. For example, any suitable mapping from SIR/SINR to MCS may be applied.
  • MCS modulation and coding scheme
  • any embodiment may be combined with other techniques for MIMO transmission control, as suitable.
  • OLA may be applied in combination with link adaptation based on the respective estimated signal quality values.
  • the gNB acquires the following information for UE u:
  • RI ⁇ b denotes Rl of the feedback from UE with index u
  • Rl denotes the pre-coder based on PMI of the feedback from UE with index u
  • SCG sub-carriergroup
  • CQI denotes CQI index of the feedback from UE with index u, wherein the CQI index can indicate wideband CQI or sub-band CQI (e.g., in accordance with 3GPP standardization).
  • H ⁇ coder g C(7 t , / r ) denotes a channel matrix estimated based on SRS for UE with index u, at sub-carriergroup (SCG) index k, wherein N r denotes the number of antennas at the UE, and
  • G C(AT t , N r ) denotes a channel matrix estimated based on SRS for UE with index u, at sub-carrier group (SCG) index k, wherein a sub-carrier used for H ⁇ coder j s different from a sub-carrier used for H s ⁇ t (see Figure 2B for illustration).
  • gNB pre-coder for beamforming based on the SRS based channel estimation (compare with sub-step 116), wherein: - rming pre-coder for UE with index u, at subcarrier group (SCG) index k, wherein L u denotes the number of layers for the UE.
  • SCG subcarrier group
  • OLA[L U ] denotes the outer loop adjustment value in dB for L u . It should be noted that the OLA values for different number of layers can be different or can be identical.
  • a general principle is that is calculated to minimize the inter-user and/or inter layer interference; i.e., it provides orthogonalization or nulling between the users and/or different MIMO layers.
  • the IpN covariance 8 ⁇ may be determined based on H ⁇ coder and the UE feedback. For example, a wideband IpN value may be provided based on the Shannon capacity with a SINR compensation factor as follows. It should be noted that this IpN covariance approach is merely an example and that other IpN estimations may be equally applicable.
  • the CQI CO! index of the UE feedback may be related to a corresponding SINR va ⁇ ue SINR u dB through a CQI- to-SINR mapping, wherein SINR ⁇ Q B denotes a wideband SINR based on CQI for UE u in dB.
  • the wideband IpN covariance may be estimated through: wherein the first term may represent the power experienced at the UE, and the second term may represent compensation.
  • N scg denotes the number of SCGs in the channel bandwidth.
  • the SINR is calculated for each UE and for each SCG.
  • the SINR is first calculated for each layer, and then converted to get the per-SCG SINR.
  • a model of the UE receiver is determined (compare with sub-step 132) by assuming, for example, MMSE reception and taking account of and the uplink channel estimation error.
  • the corresponding receiver model for UE u, at sub-carrier group (SCG) index k may be represented as: where R s k G ⁇ (N r , N r ⁇ ) is a diagonal matrix corresponding to inter-user interference caused by the uplink channel estimation error, wherein the p-th diagonal element may be expressed as
  • the signal power for the Z-th layer of UE u at the Zc-th SCG may be estimated (compare with sub-step 134) as :
  • P3® I «3('.O
  • the total signal power experienced at UE u, for the Z-th layer, at the Zc-th SCG may be represented (compare with sub-step 136) as: where
  • the per-layer per-SCG downlink SINR for the Z-th layer of the UE u, at the Zc-th SCG may be estimated (compare with sub-step 138) as:
  • the per-layer per-SCG downlink SINR may be converted to per-SCG SINR.
  • the conversions may be performed according to any suitable approach, and an example is provided as follows.
  • the information carried per carrier (ICC; e.g., spectrum efficiency or throughput) may be calculated for each layer I of UE u using a conversion function S1NR21CC as: wherein represents the set of available modulation orders. Then, the total ICC over all SCGs and all layers may be determined as: and the modulation order mod max that maximizes the total ICC (or satisfies some other suitable criterion, e.g., leading to the total ICC exceeding an ICC threshold) may be determined through:
  • the total ICC may be calculated over multiple layers for each SCG - normalized by the number of layers: and the inverse of the conversion function S1NR21CC may be used to convert from ICC to SINR to get the per-SCG SINR (compare with sub-step 140):
  • Either y u k or SlNR u k may be used for link adaptation (compare with sub-step 152).
  • Figure 2A schematically illustrates example functions according to some embodiments in the form of a functional arrangement 200.
  • the functional arrangement 200 may be seen as an exemplification of the method 100 of Figure 1.
  • the functional arrangement 200 may be seen as an exemplification of an architecture for the apparatus 300 of Figure 3 (to be described later herein).
  • a function 210 uses scheduling information (SCH) 206, user feedback (UFB) 201, uplink channel estimation (ULCE) 202, downlink transmitter pre-coder (PC) 203, an uplink channel estimation error (CEE) 207, estimated IpN 205 experienced at the UE, and outer loop adjustment values (OLA) 204 to perform SINR estimation (SINR EST) 211.
  • the downlink transmitter pre-coder may be based on the uplink channel estimation.
  • the estimated SINR is used for link adaptation (LA) 213.
  • block 201 may be compared to 112
  • block 202 may be compared to 114
  • block 203 may be compared to 116
  • block 204 may be compared to 119
  • block 205 may be compared to 117
  • block 207 may be compared to 118.
  • Block 211 may be compared to 120
  • block 213 may be compared to 152.
  • Figure 2B schematically illustrates an example sub-carrier group (SCG) 270 according to some embodiments.
  • the sub-carrier group 270 comprises first and second physical resource blocks (PRB1, PRB2) 280, 290.
  • the first and second physical resource blocks 280, 290 each comprises twelve sub-carriers (scl-scl2).
  • the uplink channel estimates used for the estimation of the downlink radio channel may relate to a sub-carrier (e.g., the first sub-carrier 281) of PRB1, when the uplink channel estimates used for the downlink beamforming precoder relate to a sub-carrier (e.g., the first sub-carrier 291) of PRB2.
  • H ⁇ coder may relate to subcarrier 291 and H ⁇ L ⁇ t may relate to sub-carrier 281.
  • FIG. 3 schematically illustrates an example apparatus 300 according to some embodiments.
  • the apparatus 300 is for a radio access node configured for communication with a plurality of users by multiple-input multiple-output (MIMO) transmission.
  • MIMO multiple-input multiple-output
  • the apparatus 300 may be comprised in the radio access node 310 as illustrated in Figure 3, in a server node (e.g., a central network node or a cloud server) controlling the radio access node, or in a control node configured to control a plurality of access points of a distributed MIMO system.
  • a server node e.g., a central network node or a cloud server
  • control node configured to control a plurality of access points of a distributed MIMO system.
  • the apparatus 300 may be configured to execute, or cause execution of, one or more method steps as described in connection with the method 100 of Figure 1.
  • the radio access node is configured to receive user feedback.
  • the radio access node is also configured to use uplink channel estimates for downlink beamforming of the MIMO transmission.
  • the apparatus 300 comprises a controller (CNTR; e.g., controlling circuitry or a control module)
  • the controller 320 is configured to cause estimation of a user-specific signal quality value (compare with step 120 of Figure 1).
  • the controller 320 may comprise, or be otherwise associated with (e.g., connected, or connectable, to) an estimator (EST; e.g., estimating circuitry or an estimation module) 322.
  • the estimator 322 may be configured to estimate the user-specific signal quality value.
  • the controller 320 is also configured to cause DL MIMO transmission to one or more user of the plurality of users based on respective estimated signal quality value (compare with step 160 of Figure 1).
  • the controller 320 may comprise, or be otherwise associated with (e.g., connected, or connectable, to) a transmitter (TX; e.g., transmitting circuitry or a transmission module) 330 of the radio access node.
  • the transmitter 330 may be configured to perform the DL MIMO transmission.
  • the controller 320 may be associated with the transmitter via a connection between the node comprising the controller 320 and the radio access node.
  • the controller 320 may be configured to cause the respective estimated signal quality value to be used for controlling MIMO configuration of an upcoming transmission occasion (compare with step 150 of Figure 1).
  • the controller 320 may be configured to cause the respective estimated signal quality value to be used for link adaptation.
  • the controller 320 may comprise, or be otherwise associated with (e.g., connected, or connectable, to) a transmission controller (TC; e.g., transmission controlling circuitry or a transmission control module) 324.
  • the transmission controller 324 may be configured to control MIMO configuration of an upcoming transmission occasion based on the respective estimated signal quality value.
  • the controller 320 may be configured to cause acquisition of information such as - for example - user feedback, UL measurements, BF setting, and OLA setting (compare with step 110 of Figure 1).
  • the controller 320 may comprise, or be otherwise associated with (e.g., connected, or connectable, to) an acquirer (ACQ; e.g., acquiring circuitry or an acquisition module) 321.
  • the acquirer 321 may be configured to acquire the information.
  • Figure 4A schematically illustrates an example communication scenario according to some embodiments.
  • the scenario of Figure 4A comprises a radio access node in the form of a base station (BS) 410 and a plurality of users in the form of UEs 411, 412, 413.
  • BS base station
  • UEs 411, 412, 413 UEs
  • the BS 410 may be configured to communicate with the UEs 411, 412, 413 by MIMO transmission. To this end, the BS 410 may comprise the apparatus 300 of Figure 3. Alternatively or additionally, the BS 410 may be configured to execute one or more steps of the method 100 of Figure 1.
  • Figure 4B schematically illustrates an example communication scenario according to some embodiments.
  • the scenario of Figure 4B comprises a radio access node in the form of a base station (BS) 420 and a plurality of users in the form of UEs 421, 422, 423.
  • the scenario of Figure 4B also comprises a server node (SN) 425.
  • the SN 425 may be a central network node or a cloud server.
  • the BS 420 may be configured to communicate with the UEs 421, 422, 423 by MIMO transmission; under the control of the SN 425.
  • the SN 425 may comprise the apparatus 300 of Figure 3.
  • the SN 425 may be configured to execute one or more steps of the method 100 of Figure 1.
  • the SN 425 may, for example, be configured to perform step 120 and provide the user-specific signal quality value(s) to the BS 420, while the BS 420 is configured to perform step 160.
  • Figure 4C schematically illustrates an example communication scenario according to some embodiments.
  • the scenario of Figure 4C comprises a plurality of radio access nodes in the form of access points (AP) 435, 436, 437 of a distributed MIMO system, and a plurality of users in the form of UEs 431, 432, 433.
  • the scenario of Figure 4C also comprises a control node (CN) 430 of the distributed MIMO system, which is configured to control the APs 435, 436, 437.
  • AP access points
  • CN control node
  • the distributed MIMO system may be configured to communicate with the UEs 431, 432, 433 by MIMO transmission; under the control of the CN 430.
  • the CN 430 may comprise the apparatus 300 of Figure 3.
  • the CN 430 may be configured to execute one or more steps of the method 100 of Figure 1.
  • the CN 430 may, for example, be configured to perform step 120 and provide the user-specific signal quality value(s) to the relevant AP(s) 435, 436, 437, which are configured to perform step 160.
  • the CN 430 may be configured to perform step 120 and the link adaptation of 160 and provide the selected MCS to the relevant AP(s) 435, 436, 437, which are configured to perform the actual transmission of step 160.
  • the described embodiments and their equivalents may be realized in software or hardware or a combination thereof.
  • the embodiments may be performed by general purpose circuitry. Examples of general purpose circuitry include digital signal processors (DSP), central processing units (CPU), co-processor units, field programmable gate arrays (FPGA) and other programmable hardware.
  • DSP digital signal processors
  • CPU central processing units
  • FPGA field programmable gate arrays
  • the embodiments may be performed by specialized circuitry, such as application specific integrated circuits (ASIC).
  • ASIC application specific integrated circuits
  • the general purpose circuitry and/or the specialized circuitry may, for example, be associated with or comprised in an apparatus such as a radio access node, a server node, or a distributed MIMO control node.
  • Embodiments may appear within an electronic apparatus (such as a radio access node, a server node, or a distributed MIMO control node) comprising arrangements, circuitry, and/or logic according to any of the embodiments described herein.
  • an electronic apparatus such as a radio access node, a server node, or a distributed MIMO control node
  • a computer program product comprises a non-transitory computer readable medium such as, for example, a universal serial bus (USB) memory, a plugin card, an embedded drive, or a read only memory (ROM).
  • Figure 5 illustrates an example computer readable medium in the form of a compact disc (CD) ROM 500.
  • the computer readable medium has stored thereon a computer program comprising program instructions.
  • the computer program is loadable into a data processor (PROC; e.g., a data processing unit) 520, which may, for example, be comprised in a device 510 (e.g., a radio access node, a server node, or a distributed MIMO control node).
  • PROC data processor
  • the computer program may be stored in a memory (MEM) 530 associated with, or comprised in, the data processor.
  • MEM memory
  • the computer program may, when loaded into, and run by, the data processor, cause execution of method steps according to, for example, the method illustrated in Figure 1, or as otherwise described herein.
  • a communication system includes a telecommunication network 610, such as a 3GPP-type cellular network, which comprises an access network 611, such as a radio access network, and a core network 614.
  • the access network 611 comprises a plurality of base stations 612a, 612b, 612c, such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 613a, 613b, 613c.
  • Each base station 612a, 612b, 612c is connectable to the core network 614 over a wired or wireless connection 615.
  • a first user equipment (UE) 691 located in coverage area 613c is configured to wirelessly connect to, or be paged by, the corresponding base station 612c.
  • a second UE 692 in coverage area 613a is wirelessly connectable to the corresponding base station 612a. While a plurality of UEs 691, 692 are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole UE is in the coverage area or where a sole UE is connecting to the corresponding base station 612.
  • the telecommunication network 610 is itself connected to a host computer 630, which may be embodied in the hardware and/or software of a standalone server, a cloud-implemented server, a distributed server or as processing resources in a server farm.
  • the host computer 630 may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service provider.
  • the connections 621, 622 between the telecommunication network 610 and the host computer 630 may extend directly from the core network 614 to the host computer 630 or may go via an optional intermediate network 620.
  • the intermediate network 620 may be one of, or a combination of more than one of, a public, private or hosted network; the intermediate network 620, if any, may be a backbone network or the Internet; in particular, the intermediate network 620 may comprise two or more sub-networks (not shown).
  • the communication system of Figure 6 as a whole enables connectivity between one of the connected UEs 691, 692 and the host computer 630.
  • the connectivity may be described as an over-the-top (OTT) connection 650.
  • the host computer 630 and the connected UEs 691, 692 are configured to communicate data and/or signaling via the OTT connection 650, using the access network 611, the core network 614, any intermediate network 620 and possible further infrastructure (not shown) as intermediaries.
  • the OTT connection 650 may be transparent in the sense that the participating communication devices through which the OTT connection 650 passes are unaware of routing of uplink and downlink communications.
  • a base station 612 may not or need not be informed about the past routing of an incoming downlink communication with data originating from a host computer 630 to be forwarded (e.g., handed over) to a connected UE 691. Similarly, the base station 612 need not be aware of the future routing of an outgoing uplink communication originating from the UE 691 towards the host computer 630.
  • a host computer 710 comprises hardware 715 including a communication interface 716 configured to set up and maintain a wired or wireless connection with an interface of a different communication device of the communication system 700.
  • the host computer 710 further comprises processing circuitry 718, which may have storage and/or processing capabilities.
  • the processing circuitry 718 may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions.
  • the host computer 710 further comprises software 711, which is stored in or accessible by the host computer 710 and executable by the processing circuitry 718.
  • the software 711 includes a host application 712.
  • the host application 712 may be operable to provide a service to a remote user, such as a UE 730 connecting via an OTT connection 750 terminating at the UE 730 and the host computer 710. In providing the service to the remote user, the host application 712 may provide user data which is transmitted using the OTT connection 750.
  • the communication system 700 further includes a base station 720 provided in a telecommunication system and comprising hardware 725 enabling it to communicate with the host computer 710 and with the UE 730.
  • the hardware 725 may include a communication interface 726 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system 700, as well as a radio interface 727 for setting up and maintaining at least a wireless connection 770 with a UE 730 located in a coverage area (not shown in Figure 7) served by the base station 720.
  • the communication interface 726 may be configured to facilitate a connection 760 to the host computer 710.
  • the connection 760 may be direct or it may pass through a core network (not shown in Figure 7) of the telecommunication system and/orthrough one or more intermediate networks outside the telecommunication system.
  • the hardware 725 of the base station 720 further includes processing circuitry 728, which may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions.
  • the base station 720 further has software 721 stored internally or accessible via an external connection.
  • the communication system 700 further includes the UE 730 already referred to.
  • Its hardware 735 may include a radio interface 737 configured to set up and maintain a wireless connection 770 with a base station serving a coverage area in which the UE 730 is currently located.
  • the hardware 735 of the UE 730 further includes processing circuitry 738, which may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions.
  • the UE 730 further comprises software 731, which is stored in or accessible by the UE 730 and executable by the processing circuitry 738.
  • the software 731 includes a client application 732.
  • the client application 732 may be operable to provide a service to a human or non-human user via the UE 730, with the support of the host computer 710.
  • an executing host application 712 may communicate with the executing client application 732 via the OTT connection 750 terminating at the UE 730 and the host computer 710.
  • the client application 732 may receive request data from the host application 712 and provide user data in response to the request data.
  • the OTT connection 750 may transfer both the request data and the user data.
  • the client application 732 may interact with the user to generate the user data that it provides.
  • the host computer 710, base station 720 and UE 730 illustrated in Figure 7 may be identical to the host computer 630, one of the base stations 612a, 612b, 612c and one of the UEs 691, 692 of Figure 6, respectively.
  • the inner workings of these entities may be as shown in Figure 7 and independently, the surrounding network topology may be that of Figure 6.
  • the OTT connection 750 has been drawn abstractly to illustrate the communication between the host computer 710 and the use equipment 730 via the base station 720, without explicit reference to any intermediary devices and the precise routing of messages via these devices.
  • Network infrastructure may determine the routing, which it may be configured to hide from the UE 730 or from the service provider operating the host computer 710, or both. While the OTT connection 750 is active, the network infrastructure may further take decisions by which it dynamically changes the routing (e.g., on the basis of load balancing consideration or reconfiguration of the network).
  • the wireless connection 770 between the UE 730 and the base station 720 is in accordance with the teachings of the embodiments described throughout this disclosure.
  • One or more of the various embodiments improve the performance of OTT services provided to the UE 730 using the OTT connection 750, in which the wireless connection 770 forms the last segment. More precisely, the teachings of these embodiments may improve the throughput and thereby provide benefits such as one or more of: reduced user waiting time, relaxed restriction on file size, and better responsiveness.
  • a measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve.
  • the measurement procedure and/or the network functionality for reconfiguring the OTT connection 750 may be implemented in the software 711 of the host computer 710 or in the software 731 of the UE 730, or both.
  • sensors (not shown) may be deployed in or in association with communication devices through which the OTT connection 750 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software 711, 731 may compute or estimate the monitored quantities.
  • the reconfiguring of the OTT connection 750 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not affect the base station 720, and it may be unknown or imperceptible to the base station 720. Such procedures and functionalities may be known and practiced in the art.
  • measurements may involve proprietary UE signaling facilitating the host computer's 710 measurements of throughput, propagation times, latency and the like. The measurements may be implemented in that the software 711, 731 causes messages to be transmitted, in particular empty or 'dummy' messages, using the OTT connection 750 while it monitors propagation times, errors etc.
  • FIGURE 8 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment.
  • the communication system includes a host computer, a base station and a UE which may be those described with reference to Figures 6 and 7. For simplicity of the present disclosure, only drawing references to Figure 8 will be included in this section.
  • the host computer provides user data.
  • the host computer provides the user data by executing a host application.
  • the host computer initiates a transmission carrying the user data to the UE.
  • the base station transmits to the UE the user data which was carried in the transmission that the host computer initiated, in accordance with the teachings of the embodiments described throughout this disclosure.
  • the UE executes a client application associated with the host application executed by the host computer.
  • FIGURE 9 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment.
  • the communication system includes a host computer, a base station and a UE which may be those described with reference to Figures 6 and 7. For simplicity of the present disclosure, only drawing references to Figure 9 will be included in this section.
  • the host computer provides user data.
  • the host computer provides the user data by executing a host application.
  • the host computer initiates a transmission carrying the user data to the UE. The transmission may pass via the base station, in accordance with the teachings of the embodiments described throughout this disclosure.
  • the UE receives the user data carried in the transmission.
  • all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is clearly given and/or is implied from the context in which it is used.
  • the method embodiments described herein discloses example methods through steps being performed in a certain order. However, it is recognized that these sequences of events may take place in another order without departing from the scope of the claims. Furthermore, some method steps may be performed in parallel even though they have been described as being performed in sequence. Thus, the steps of any methods disclosed herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as following or preceding another step and/or where it is implicit that a step must follow or precede another step.
  • a base station configured to communicate with a user equipment ( U E), wherein the base station is a radio access node configured for communication with a plurality of users by multiple-input multiple-output, MIMO, transmission, wherein the UE is one of the plurality of users, wherein the radio access node is configured to receive user feedback, and wherein the radio access node is configured to use uplink channel estimates for downlink beamforming of the MIMO transmission, the base station comprising a radio interface and processing circuitry configured to: estimate a user-specific signal quality value, wherein the signal quality value is a signal-to- interference ratio, SIR, value and/or a signal-to-interference-and-noise ratio, SINR, value; and perform or cause downlink MIMO transmission to one or more user of the plurality of users based on respective estimated signal quality value, wherein estimating the signal quality value comprises combining a desired power component and a total power component, wherein the desired power component is determined from an extended downlink channel model, wherein the total power component is determined from
  • a communication system including a host computer comprising: processing circuitry configured to provide user data; and a communication interface configured to forward the user data to a cellular network for transmission to a user equipment (UE), wherein the cellular network comprises a base station configured to communicate with the UE, wherein the base station is a radio access node configured for communication with a plurality of users by multiple-input multiple-output, MIMO, transmission, wherein the UE is one of the plurality of users, wherein the radio access node is configured to receive user feedback, and wherein the radio access node is configured to use uplink channel estimates for downlink beamforming of the MIMO transmission, the base station having a radio interface and processing circuitry, the base station's processing circuitry configured to: estimate a user-specific signal quality value, wherein the signal quality value is a signal-to- interference ratio, SIR, value and/or a signal-to-interference-and-noise ratio, SINR, value; and perform or cause downlink MIMO transmission to one or more user of the plurality
  • the processing circuitry of the host computer is configured to execute a host application, thereby providing the user data; and the UE comprises processing circuitry configured to execute a client application associated with the host application.
  • a method implemented in a base station configured to communicate with a user equipment (UE), wherein the base station is a radio access node configured for communication with a plurality of users by multiple-input multiple-output, MIMO, transmission, wherein the UE is one of the plurality of users, wherein the radio access node is configured to receive user feedback, and wherein the radio access node is configured to use uplink channel estimates for downlink beamforming of the MIMO transmission, the method comprising: estimating a user-specific signal quality value, wherein the signal quality value is a signa I- to-interference ratio, SIR, value and/or a signal-to-interference-and-noise ratio, SINR, value; and performing or causing downlink MIMO transmission to one or more user of the plurality of users based on respective estimated signal quality value, wherein estimating the signal quality value comprises combining a desired power component and a total power component, wherein the desired power component is determined from an extended downlink channel model, wherein the total power component is determined from the extended
  • a method implemented in a communication system including a host computer, a base station and a user equipment (UE), wherein the base station is configured to communicate with the UE, wherein the base station is a radio access node configured for communication with a plurality of users by multiple-input multiple-output, MIMO, transmission, wherein the UE is one of the plurality of users, wherein the radio access node is configured to receive user feedback, and wherein the radio access node is configured to use uplink channel estimates for downlink beamforming of the MIMO transmission, the method comprising: estimating a user-specific signal quality value, wherein the signal quality value is a signa I- to-interference ratio, SIR, value and/or a signal-to-interference-and-noise ratio, SINR, value; and performing or causing downlink MIMO transmission to one or more user of the plurality of users based on respective estimated signal quality value, wherein estimating the signal quality value comprises combining a desired power component and a total power component, wherein the desired power component

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Abstract

Est divulgué un procédé pour un nœud d'accès radio. Le procédé permet de communiquer avec une pluralité d'utilisateurs par transmission à entrées multiples et sorties multiples (MIMO). Le nœud d'accès radio est configuré pour recevoir une rétroaction d'utilisateur, et pour utiliser des estimations de canal de liaison montante pour la formation de faisceau de liaison descendante de la transmission MIMO. Le procédé consiste à estimer une valeur de qualité de signal spécifique à l'utilisateur, la valeur de qualité de signal étant une valeur de rapport signal/brouillage (SIR) et/ou une valeur de rapport signal/brouillage et bruit (SINR), et à effectuer ou à provoquer une transmission MIMO de liaison descendante à un ou plusieurs utilisateurs de la pluralité d'utilisateurs sur la base d'une valeur de qualité de signal estimée respective. L'estimation de la valeur de qualité de signal comprend la combinaison d'une composante de puissance souhaitée et d'une composante de puissance totale. La composante de puissance souhaitée est déterminée à partir d'un modèle de canal de liaison descendante étendu, le modèle de canal de liaison descendante étendu étant une combinaison d'un précodeur de formation de faisceau de liaison descendante, d'une estimation d'un canal radio de liaison descendante, et d'un modèle de récepteur du ou des utilisateurs déterminés sur la base de la rétroaction d'utilisateur. La composante de puissance totale est déterminée à partir du modèle de canal de liaison descendante étendu, et est compensée par rapport à des incertitudes de l'estimation de canal de liaison montante et/ou des perturbations estimées au niveau de l'utilisateur. Par exemple, une transmission MIMO DL peut comprendre l'utilisation de la valeur SIR et/ou de la valeur SINR ajustées pour une adaptation de liaison. Sont également divulgués un produit-programme informatique, un appareil, un nœud d'accès radio, un nœud de serveur et un nœud de commande MIMO distribué correspondants.
PCT/EP2022/080813 2022-11-04 2022-11-04 Approches de transmission mimo WO2024094310A1 (fr)

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