WO2024055150A1 - Procédé, nœud de réseau et programme informatique pour l'étalonnage d'air d'un système d'antenne active - Google Patents

Procédé, nœud de réseau et programme informatique pour l'étalonnage d'air d'un système d'antenne active Download PDF

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WO2024055150A1
WO2024055150A1 PCT/CN2022/118414 CN2022118414W WO2024055150A1 WO 2024055150 A1 WO2024055150 A1 WO 2024055150A1 CN 2022118414 W CN2022118414 W CN 2022118414W WO 2024055150 A1 WO2024055150 A1 WO 2024055150A1
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Prior art keywords
reference signals
downlink reference
user equipment
antenna system
active antenna
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PCT/CN2022/118414
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English (en)
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Hao Zhang
Ang FENG
Henrik Asplund
Christian Braun
Ming Li
Georgy LEVIN
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Telefonaktiebolaget Lm Ericsson (Publ)
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Priority to PCT/CN2022/118414 priority Critical patent/WO2024055150A1/fr
Publication of WO2024055150A1 publication Critical patent/WO2024055150A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/10—Monitoring; Testing of transmitters
    • H04B17/11—Monitoring; Testing of transmitters for calibration
    • H04B17/12—Monitoring; Testing of transmitters for calibration of transmit antennas, e.g. of the amplitude or phase
    • 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
    • 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
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0617—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal for beam forming

Definitions

  • Embodiments presented herein relate to a method, a network node, a computer program, and a computer program product for over the air calibration of an active antenna system.
  • Massive Multiple-Input Multiple-Output (MIMO) technologies can be used to boost capacity or enlarge coverage of wireless communication systems. These benefits are accomplished by beamforming, a functionality that can concentrate the radiation wave carrying transmitted signals at some specific directions to strengthen the signal power at the receiver side. To enable beamforming, the signals from multiple antenna elements need to be aligned coherently. In general terms, coherency refers to that the phase and amplitude response is the same for all antenna branches involved in the beamforming. Coherency is commonly difficult to be guaranteed by hardware alone. Therefore, Antenna Calibration (AC) is employed in Active Antenna Systems (AAS) , sometimes also referred to as advanced antenna systems. Two examples of AC are coupler-based AC and mutual coupling-based AC.
  • AAS Active Antenna Systems
  • OTA AC Over-the-Air
  • UE user equipment
  • CSI Channel State Information
  • RS reference signals
  • An object of embodiments herein is to overcome the above noted issues, and in particular to provide OTA AC of an AAS that does not suffer from the above issues.
  • a method for over the air calibration of an AAS is performed by a network node.
  • the method comprises estimating uplink channel properties from measurements made on uplink reference signals received over a wireless channel by the AAS from a UE.
  • the method comprises precoding and transmitting downlink reference signals towards the UE from the AAS.
  • the downlink reference signals are precoded according to information derived from the uplink channel properties.
  • the method comprises receiving a report from the UE of measurements made by the UE on the downlink reference signals.
  • the method comprises calibrating the AAS as a function of the measurements made by the UE.
  • a network node for over the air calibration of an AAS.
  • the network node comprises processing circuitry.
  • the processing circuitry is configured to cause the network node to estimate uplink channel properties from measurements made on uplink reference signals received over a wireless channel by the AAS from a UE.
  • the processing circuitry is configured to cause the network node to precode and transmitting downlink reference signals towards the UE from the AAS.
  • the downlink reference signals are precoded according to information derived from the uplink channel properties.
  • the processing circuitry is configured to cause the network node to receive a report from the UE of measurements made by the UE on the downlink reference signals.
  • the processing circuitry is configured to cause the network node to calibrate the AAS as a function of the measurements made by the UE.
  • a network node for OTA calibration of an AAS.
  • the network node comprises an estimate module configured to estimate uplink channel properties from measurements made on uplink reference signals received over a wireless channel by the AAS from a UE.
  • the network node comprises a precode module configured to precode and transmitting downlink reference signals towards the UE from the AAS.
  • the downlink reference signals are precoded according to information derived from the uplink channel properties.
  • the network node comprises a receive module configured to receive a report from the UE of measurements made by the UE on the downlink reference signals.
  • the network node comprises a calibrate module configured to calibrate the AAS as a function of the measurements made by the UE.
  • a computer program for OTA calibration of an AAS comprising computer program code which, when run on a network node, causes the network node to perform a method according to the first aspect.
  • a computer program product comprising a computer program according to the fourth aspect and a computer readable storage medium on which the computer program is stored.
  • the computer readable storage medium could be a non-transitory computer readable storage medium.
  • these aspects provide efficient OTA calibration of an AAS, without suffering from the above issues.
  • these aspects enable acquisition of accurate downlink CSI feedback for OTA AC with small overhead and lower computation load at the UE.
  • these aspects enable efficient reciprocity calibration for an AAS at one single transmission and reception point or an AAS spread between two or more transmission and reception points (TRP) , as used in distributed MIMO systems.
  • these aspects do not require any special configuration for the UE or for downlink CSI feedback.
  • these aspects support OTA AC for an AAS with large number of antenna elements with limited reference signal (RS) resource.
  • RS reference signal
  • these aspects enable triggering of the reference signal transmission for OTA AC to not disturb regular transmissions.
  • Fig. 1 is a schematic diagram illustrating a communication network according to embodiments
  • Fig. 2 schematically illustrates uplink aspects of UE assisted OTA AC according to an embodiment
  • Fig. 3 schematically illustrates downlink aspects of UE assisted OTA AC according to an embodiment
  • Fig. 4 is a flowchart of methods according to embodiments.
  • Fig. 5 shows an example Doppler spectrum according to an embodiment
  • Fig. 6 shows simulation results without OTA channel mitigation according to an embodiment
  • Fig. 7 shows simulation results with OTA channel mitigation according to an embodiment
  • Fig. 8 schematically illustrates a mapping between downlink reference signal resources and antenna elements according to a first embodiment
  • Fig. 9 schematically illustrates a mapping between downlink reference signal resources and antenna elements according to a second embodiment
  • Fig. 10 schematically illustrates scheduling of uplink reference signals and precoded downlink reference signals according to an embodiment
  • Fig. 11 is a signaling diagram according to an embodiment
  • Fig. 12 is a schematic diagram showing functional units of a network node according to an embodiment
  • Fig. 13 is a schematic diagram showing functional modules of a network node according to an embodiment.
  • Fig. 14 shows one example of a computer program product comprising computer readable storage medium according to an embodiment.
  • Fig. 1 is a schematic diagram illustrating a communication network 100 where embodiments presented herein can be applied.
  • the communication network 100 comprises an access network 110 in which wireless access is provided to UE 170 by one or more AAS 140.
  • the AAS 140 is operatively controlled by a network node 200. It is here noted that although illustrated as being arranged at one transmission and reception point, the AAS 140 might be distributed between two or more transmission and reception points within the access network 110.
  • the network node 200 and one or more AAS 140 might collectively form an access network node, radio base station, base transceiver station, node B (NB) , evolved node B (eNB) , gNB, access point, or integrated access and backhaul (IAB) node.
  • NB node B
  • eNB evolved node B
  • gNB access point
  • IAB integrated access and backhaul
  • the UE 170 might be any of a portable wireless device, mobile station, mobile phone, handset, wireless local loop phone, smartphone, laptop computer, tablet computer, network equipped vehicle, network equipped sensor, Internet of Things (IoT) device, game controller, etc. As is understood, a plurality of UEs 170 might be served by one or more AAS 140 and/or network nodes 200.
  • the access network 110 is via the network node 200 operatively connected to a service network 130, such as the Internet, via a core network 120.
  • the UE 170 is thereby enabled to access service and data made accessible in the service network 130.
  • radio branches are to be calibrated in the AAS 140. Assume further that each radio branch is connected to one or more physical antennas (for example provided in a subarray arrangement) via a physical antenna port.
  • the UE 170 should feedback its measurement of the downlink channel via CSI feedback to the network side.
  • the network side As noted above, there is still a need for an improved OTA AC of an AAS.
  • Downlink CSI feedback requires large overhead for accurate CSI to be reported by the UE for some OTA channels, such as non-line of sight channels with large angular spread.
  • the OTA channel is the wireless channel between the AAS and the UE, from transmitter antenna (s) to receiver antenna (s) , not taking into consideration any internal channels in the transmitter or receiver.
  • Some techniques for OTA AC of requires advanced processing and high computation load at the UE side.
  • the mapping between ports for the downlink reference signals and antenna elements is not designed for OTA AC.
  • one port for downlink reference signals might be mapped to multiple antenna elements, or to two polarizations.
  • the scheduling for downlink and uplink reference signals might not be predictable enough for OTA AC. For example, some reference signals might not be transmitted when there is no UE traffic.
  • the embodiments disclosed herein therefore relate to techniques for OTA calibration of an AAS 140.
  • a network node 200 a method performed by the network node 200, a computer program product comprising code, for example in the form of a computer program, that when run on a network node 200, causes the network node 200 to perform the method.
  • At least some of the herein disclosed embodiments relate to techniques for controlling and scheduling reference signal resources for UE assisted OTA AC. This can be used to reduce the overhead of the feedback channel from the UE to the network node as well as the computational complexity of the UE. In some aspects, this is achieved by exploiting reciprocity of the wireless channel between the AAS and the UE.
  • At least some of the herein disclosed embodiments are based on precoding of downlink reference signals that exploits the reciprocity of the wireless channel, as well as scheduling of uplink and downlink reference signals for AC purposes.
  • Fig. 2 shows uplink aspects of UE assisted OTA AC.
  • Fig. 3 shows downlink aspects of UE assisted OTA AC.
  • H OTA is used to express both of them.
  • the symbol denotes the Hadamard division
  • the symbol “ ⁇ ” denotes the Hadamard multiplication, i.e., the element-wise division and multiplication of vectors and matrices.
  • k denotes physical resource block (PRB) index. Since H UE is common for all received signals at the network side (where the purpose of the AC is to find, and compensate, relative differences between radio branches at the AAS side) , the relative CSI can be simplified as
  • H OTA is a matrix which contains elements for every physical antenna and every PRB. From the above follows that H OTA (k, n) can be expressed as:
  • mappings between downlink reference signal ports and antenna elements in the AAS will be disclosed below.
  • the downlink channel can be expressed as:
  • Fig. 4 is a flowchart illustrating embodiments of methods for OTA calibration of an AAS 140.
  • the methods are performed by the network node 200.
  • the methods are advantageously provided as computer programs 1420.
  • the network node 200 estimates uplink channel properties.
  • the uplink channel properties are estimated from measurements made on uplink reference signals received over a wireless channel by the AAS 140 from the UE 170.
  • the network node 200 precodes and transmits downlink reference signals towards the UE 170 from the AAS 140.
  • the downlink reference signals are precoded according to information derived from the uplink channel properties.
  • the network node 200 receives a report from the UE 170 of measurements made by the UE 170 on the downlink reference signals.
  • the network node 200 calibrates the AAS 140 as a function of the measurements made by the UE 170.
  • the precoding is performed to eliminate channel effects in measurements made by the UE on the downlink reference signals so that the downlink CSI feedback can be used for antenna calibration purposes. That is, in some embodiments, the downlink reference signals are precoded with an objective to eliminate effects (on the wireless channel) caused by the downlink channel properties. In some aspects, the precoding is performed with an objective to expose the uplink AC error to the UE so that the AAS reciprocity error can be measured by the UE. In particular, in some embodiments, the downlink reference signals are precoded with an objective for the UE 170 to measure a reciprocity error of the AAS 140.
  • the precoding is performed so that the downlink reference signals as received by the UE appear to come from the line of sight boresight direction.
  • the downlink reference signals are precoded with an objective to appear to have been transmitted towards the UE 170 from the AAS 140 in a boresight line of sight direction.
  • the uplink channel properties between the UE 170 and the AAS 140 are composed of a first part H UE representing channel impairments caused by the UE 170, a second part H OTA representing channel impairments caused by the wireless channel from the UE 170 to the AAS 140, and a third part representing uplink channel impairments caused by the AAS 140.
  • H UE is common or same for all BS antennas so it can be ignored in following procedures for the purpose of BS AC.
  • the reciprocity of the OTA channel is exploited to reduce the overhead in the feedback channel from the UE and the complexity at the UE side.
  • the channel properties correspond to the full uplink channel properties except the impairments caused by the UE.
  • S (k, n) [S 1 (k, n) , S 2 (k, n) , ..., S M (k, n) ] , where S (k, 1) , S (k, 2) , ..., S (k, N) are orthogonal signals, denoting the root sequence of the downlink reference signals which contains multiple reference signal ports on every PRB.
  • N is the number of reference signal ports.
  • M is the number of resource elements for each reference signal port.
  • S (k, n) can be divided by the OTA CSI, i.e., H OTA (k, n) and the UL AC error, i.e., to generate the precoded downlink reference signal sequence X (k, n) .
  • the network node transmits the downlink reference signals towards the UE (as illustrated in Fig. 3) .
  • Y (k, n) [Y 1 (k, n) , Y 2 (k, n) , ..., Y M (k, n) ] the received downlink reference signals by the UE. This leaves only the reciprocity error in the channel estimation for the UE.
  • the UE feeds back the reciprocity error to the network node. This procedure can be summarized in equations as follows:
  • the channel properties correspond to the uplink OTA part.
  • S (k, n) can be divided by H OTA (k, n) to generate the precoded downlink reference signal sequence X (k, n) .
  • the network node After the precoding, the network node transmits the downlink reference signals towards the UE. This leaves only the factor in the channel estimation for the UE. Finally, the UE feeds back the downlink AC error, in which the impact of downlink wireless channel is removed.
  • each downlink reference signal port is precoded with different information. Then, the network node transmits these precoded downlink reference signal at corresponding ports towards the UE for that the UE can extract each reference signal separately for estimation only of the AAS AC error.
  • channel properties correspond to uplink impairments caused by the AAS.
  • This corresponds to an embodiment where the information is derived from the third part (whilst ignoring the first part H UE and removing the second part H OTA ) .
  • S (k, n) can be divided by to generate the precoded downlink reference signal sequence X (k, n) .
  • the network node After the precoding, the network node transmits the downlink reference signals towards the UE. This leaves the OTA channel and in the channel estimation for the UE. Finally, the UE feeds back the OTA CSI and reciprocity error. This procedure can be summarized in equations as follows:
  • the downlink reference signals are precoded according to information derived from the uplink channel properties under an assumption of channel reciprocity of the wireless channel.
  • the channel reciprocity should be consistent.
  • a channel can be reciprocal if the rate of change between the time of uplink (UL) and downlink (DL) transmission is small.
  • the Doppler shift of H OTA can be computed as below.
  • the variable t is the time interval of the received uplink reference signal.
  • H OTA [H OTA (k, n, 1) , H OTA (k, n, 2) , ..., H OTA (k, n, t) ]
  • H dop (k, n, i) FFT (H OTA )
  • FFT H OTA
  • H OTA Fast Fourier Transform
  • the Doppler spectrum P is estimated as follows:
  • N fft is the number of FFT bins.
  • the Doppler shift is denoted by I which is the index of the peak of the Doppler spectrum P.
  • Fig. 5 shows an example Doppler spectrum of the OTA CSI, where it can be observed that Doppler shift can be accurately evaluated by the index of the peak.
  • the downlink reference signals can be precoded according to information derived from the uplink channel properties under an assumption of channel reciprocity of the wireless channel.
  • the assumption of channel reciprocity is confirmed by a Doppler shift, I representing a peak in the Doppler spectrum, of the second part H OTA being smaller than a threshold value.
  • the threshold value might be determined according to simulations, or tests.
  • Fig. 6 shows simulation results without OTA channel mitigation.
  • Fig. 7 shows simulation results with OTA channel mitigation using the above disclosed second embodiment.
  • Each curve represents the CSI phase response of one antenna element.
  • Fig. 6 shows the CSI as affected by the OTA channel and the AC error, where the former contains angular spread (AS) and delay spread (DS) from the wireless channels.
  • AS angular spread
  • DS delay spread
  • a large overhead is needed for the feedback channel and a high computation load is needed for the UE.
  • Fig. 7 shows the CSI as affected only by the AC error only, yielding a much lower AS and DS. In turn, this significantly reduces the overhead for the feedback channel and the computation load for the UE.
  • the above disclosed first embodiment yields even better results, i.e., lower frequency variation, than the second embodiment.
  • mapping between reference signal resources and antenna elements is used for this purpose. Aspects of such mappings will be disclosed next. If there is a one-to-one mapping between reference signal resources and antenna elements, then the CSI for every antenna element of the AAS can be acquired from the CSI feedback from the UE.
  • the AAS 140 might comprises antenna branches of one or more polarizations. In some embodiments, per each time instant the downlink reference signals are transmitted, one downlink reference signal resource is transmitted on each antenna branch of each polarization.
  • the downlink reference signal resources e.g., 32 CSI-RS ports
  • the 32 CSI-RS ports are transmitted in the antenna elements of polarization 1
  • the 32 CSI-RS ports are transmitted in the antenna elements of polarization 2.
  • the UE estimates and feeds back the CSI to the network node based on the received CSI-RS.
  • the AAS comprises 128 antenna branches or more, as shown in Fig. 9, a switch is made between different subsets of antenna elements.
  • the 32 CSI-RS ports are mapped to one such subset to provide direction of departure (DoD) processing. If the 32 CSI-RS ports are mapped to a stochastic subarray arrangement, the DoD information would be lost. Therefore, in some embodiments, the antenna branches of the AAS 140 are divided in partly overlapping subsets.
  • the downlink reference signals are transmitted in downlink reference signal resources, where, per each time instant the downlink reference signals are transmitted, one downlink reference signal resource is transmitted per each of the antenna branches of only one of the subsets. A switch is made from one subset to another between consecutive time instants in which the downlink reference signals are transmitted.
  • the uplink reference signals and the precoded downlink reference signals are only transmitted if either the UE traffic is not predicable or there is no UE traffic at all.
  • the network node is configured to perform (optional) step S102:
  • the network node schedules transmission of the uplink reference signals and transmission of the precoded downlink reference signals.
  • the uplink reference signals and the precoded downlink reference signals are scheduled to be transmitted when traffic for the UE 170 is either unpredictable or absent.
  • the uplink reference signals are scheduled to be transmitted before the precoded downlink reference signals.
  • SRS is short for sounding reference signal and is an example of an uplink reference signal
  • “DL CSI Feedback” represents channel feedback sent by the UE.
  • the precoded downlink reference signals (represented by the CSI-RS) might need to be transmitted at multiple time instants together with a defined mapping to the antenna elements, to complete all the antenna branches and polarizations.
  • Scheduling 1 is suitable for an AAS with a comparatively small number of antenna elements
  • Scheduling 2 is suitable for a comparatively larger number of antenna elements.
  • the precoded downlink reference signals and the uplink reference signals need to be transmitted repeatedly (in three different beams) to keep the OTA channel reciprocity.
  • Scheduling 2 continues with transmission of CSI-RS in beam 2 using polarization 2 after the last illustrated “DL CSI Feedback” , and so on until CSI-RS has been transmitted in all three beams using polarization 2.
  • Aspects of quality checking of report from the UE of measurements made by the UE will be disclosed next.
  • the network node For checking if the received measurements are usable for antenna calibration purposes, the network node might check the Channel Quality Indicator (CQI) , if reported from the UE to determine if the CSI feedback is usable for AC purposes.
  • CQI Channel Quality Indicator
  • the network node determines the CSI quality for UEs configured with a lowMobilityEvaluation criterion.
  • the network node determines the CSI quality for UEs configured with both a lowMobilityEvaluation criterion and a cellEdgeEvaluation criterion whereas the combineRelaxedMeasCondition criterion is not configured, and the UE (s) has fulfilled only the lowMobilityEvaluation criterion.
  • the network node determines that the measurements are usable for antenna calibration purposes if the UE reports a signal to interference ratio (SNR) being higher than some threshold value, where the threshold value can be predefined or configured by the network node.
  • the UE transmits uplink reference signals that are received at the AAS.
  • the network node performs uplink processing on the received uplink reference signals.
  • the network node performs downlink processing by precoding and transmitting downlink reference signals towards the UE from the AAS.
  • the downlink reference signals are precoded according to information derived from the uplink channel properties.
  • the precoded downlink reference signals are received by the UE.
  • S204a, S204b The UE makes measurements on the received downlink reference signals to perform channel estimation and compression on the received precoded downlink reference signals and feeds back reports of the measurements to the network node.
  • the network node checks the received measurements and performs AC as a function of the measurements.
  • Fig. 12 schematically illustrates, in terms of a number of functional units, the components of a network node 200 according to an embodiment.
  • Processing circuitry 210 is provided using any combination of one or more of a suitable central processing unit (CPU) , multiprocessor, microcontroller, digital signal processor (DSP) , etc., capable of executing software instructions stored in a computer program product 1410 (as in Fig. 14) , e.g., in the form of a storage medium 230.
  • the processing circuitry 210 may further be provided as at least one application specific integrated circuit (ASIC) , or field programmable gate array (FPGA) .
  • ASIC application specific integrated circuit
  • FPGA field programmable gate array
  • the processing circuitry 210 is configured to cause the network node 200 to perform a set of operations, or steps, as disclosed above.
  • the storage medium 230 may store the set of operations
  • the processing circuitry 210 may be configured to retrieve the set of operations from the storage medium 230 to cause the network node 200 to perform the set of operations.
  • the set of operations may be provided as a set of executable instructions.
  • the processing circuitry 210 is thereby arranged to execute methods as herein disclosed.
  • the storage medium 230 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.
  • the network node 200 may further comprise a communications interface 220 at least configured for communications with other entities, functions, nodes, and devices, as illustrated in Fig. 1.
  • the communications interface 220 may comprise one or more transmitters and receivers, comprising analogue and digital components.
  • the processing circuitry 210 controls the general operation of the network node 200 e.g., by sending data and control signals to the communications interface 220 and the storage medium 230, by receiving data and reports from the communications interface 220, and by retrieving data and instructions from the storage medium 230.
  • Other components, as well as the related functionality, of the network node 200 are omitted in order not to obscure the concepts presented herein.
  • Fig. 13 schematically illustrates, in terms of a number of functional modules, the components of a network node 200 according to an embodiment.
  • the network node 200 of Fig. 13 comprises a number of functional modules; an estimate module 210b configured to perform step S104, a precode module 210c configured to perform step S106, a receive module 210d configured to perform step S108, and a calibrate module 210e configured to perform step S110.
  • the network node 200 of Fig. 13 may further comprise a number of optional functional modules, such as a schedule module 210a configured to perform step S102.
  • each functional module 210a: 210e may in one embodiment be implemented only in hardware and in another embodiment with the help of software, i.e., the latter embodiment having computer program instructions stored on the storage medium 230 which when run on the processing circuitry makes the network node 200 perform the corresponding steps mentioned above in conjunction with Fig 13. It should also be mentioned that even though the modules correspond to parts of a computer program, they do not need to be separate modules therein, but the way in which they are implemented in software is dependent on the programming language used.
  • one or more or all functional modules 210a: 210e may be implemented by the processing circuitry 210, possibly in cooperation with the communications interface 220 and/or the storage medium 230.
  • the processing circuitry 210 may thus be configured to from the storage medium 230 fetch instructions as provided by a functional module 210a: 210e and to execute these instructions, thereby performing any steps as disclosed herein.
  • the network node 200 may be provided as a standalone device or as a part of at least one further device.
  • the network node 200 may be integrated with the AAS.
  • functionality of the network node 200 may be distributed between at least two devices, or nodes. These at least two nodes, or devices, may either be part of the same network part (such as the access network or the core network) or may be spread between at least two such network parts.
  • instructions that are required to be performed in real time may be performed in a device, or node, operatively closer to the cell than instructions that are not required to be performed in real time.
  • a first portion of the instructions performed by the network node 200 may be executed in a first device, and a second portion of the of the instructions performed by the network node 200 may be executed in a second device; the herein disclosed embodiments are not limited to any particular number of devices on which the instructions performed by the network node 200 may be executed.
  • the methods according to the herein disclosed embodiments are suitable to be performed by a network node 200 residing in a cloud computational environment. Therefore, although a single processing circuitry 210 is illustrated in Fig. 12 the processing circuitry 210 may be distributed among a plurality of devices, or nodes. The same applies to the functional modules 210a: 210e of Fig. 13 and the computer program 1420 of Fig. 14.
  • Fig. 14 shows one example of a computer program product 1410 comprising computer readable storage medium 1430.
  • a computer program 1420 can be stored, which computer program 1420 can cause the processing circuitry 210 and thereto operatively coupled entities and devices, such as the communications interface 220 and the storage medium 230, to execute methods according to embodiments described herein.
  • the computer program 1420 and/or computer program product 1410 may thus provide means for performing any steps as herein disclosed.
  • the computer program product 1410 is illustrated as an optical disc, such as a CD (compact disc) or a DVD (digital versatile disc) or a Blu-Ray disc.
  • the computer program product 1410 could also be embodied as a memory, such as a random access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM) , or an electrically erasable programmable read-only memory (EEPROM) and more particularly as a non-volatile storage medium of a device in an external memory such as a USB (Universal Serial Bus) memory or a Flash memory, such as a compact Flash memory.
  • the computer program 1420 is here schematically shown as a track on the depicted optical disk, the computer program 1420 can be stored in any way which is suitable for the computer program product 1410.

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  • Radio Transmission System (AREA)

Abstract

L'invention concerne des techniques pour l'étalonnage de l'air d'un système d'antenne active. Un procédé est mis en œuvre par un nœud de réseau. Le procédé comprend l'estimation de propriétés de canal de liaison montante à partir de mesures effectuées sur des signaux de référence de liaison montante reçus sur un canal sans fil par le système d'antenne active à partir d'un équipement utilisateur. Le procédé comprend le précodage et la transmission de signaux de référence de liaison descendante vers l'équipement utilisateur à partir du système d'antenne active. Les signaux de référence de liaison descendante sont précodés selon des informations dérivées des propriétés de canal de liaison montante. Le procédé comprend la réception d'un rapport en provenance de l'équipement utilisateur de mesures effectuées par l'équipement utilisateur sur les signaux de référence de liaison descendante. Le procédé comprend l'étalonnage du système d'antenne active en fonction des mesures effectuées par l'équipement utilisateur.
PCT/CN2022/118414 2022-09-13 2022-09-13 Procédé, nœud de réseau et programme informatique pour l'étalonnage d'air d'un système d'antenne active WO2024055150A1 (fr)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2448137A1 (fr) * 2009-06-23 2012-05-02 Alcatel Lucent Procédé et dispositif d'émission de signaux dans un système mimo à duplexage par répartition temporelle
US11108442B1 (en) * 2018-07-20 2021-08-31 Qualcomm Incorporated Calibration and implicit sounding using multi user multiple input multiple output transmissions

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2448137A1 (fr) * 2009-06-23 2012-05-02 Alcatel Lucent Procédé et dispositif d'émission de signaux dans un système mimo à duplexage par répartition temporelle
US11108442B1 (en) * 2018-07-20 2021-08-31 Qualcomm Incorporated Calibration and implicit sounding using multi user multiple input multiple output transmissions

Non-Patent Citations (4)

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Title
CHOPRA RIBHU ET AL: "Blind Channel Estimation for Downlink Massive MIMO Systems With Imperfect Channel Reciprocity", IEEE TRANSACTIONS ON SIGNAL PROCESSING, IEEE, USA, vol. 68, 19 April 2020 (2020-04-19), pages 3132 - 3145, XP011794006, ISSN: 1053-587X, [retrieved on 20200615], DOI: 10.1109/TSP.2020.2988570 *
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SHAHABI SEYYED MOHAMMADMAHDI ET AL: "A Novel Calibration Error Aware Precoding for Massive MIMO Systems with Imperfect CSI", 2019 27TH IRANIAN CONFERENCE ON ELECTRICAL ENGINEERING (ICEE), IEEE, 30 April 2019 (2019-04-30), pages 1687 - 1691, XP033588960, DOI: 10.1109/IRANIANCEE.2019.8786546 *
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