Method, apparatus and computer program technical field

Abstract

There is provided a method, apparatus, and computer program for causing at least the following to be performed: receiving, by a user device, an indication that triggers uplink link adaptation calibration to be performed; and obtaining, by the user device, a block of N downlink channel state information reference signals for uplink link adaptation calibration based on the indication.

Description

METHOD, APPARATUS AND COMPUTER PROGRAM TECHNICAL FIELD

[0001] Various example embodiments of this disclosure relate to a method, apparatus, system and computer program and in particular but not exclusively to link adaptation (LA). BACKGROUND

[0002] A communication network can be seen as a facility that enables communications between two or more communication devices, or provides communication devices access to a data network. A mobile or wireless communication network is one example of a communication network. A communication device may be provided with a service by an application server.

[0003] Such communication networks operate in according with standards such as those provided by 3GPP (Third Generation Partnership Project) or ETSI (European Telecommunications Standards Institute). Examples of standards are the so-called 5G (5th Generation) standards and 6G (6th Generation) standards provided by 3GPP. SUMMARY

[0004] Some example embodiments of this disclosure will be described with respect to certain aspects. These aspects are not intended to indicate key or essential features of the embodiments of this disclosure, nor are they intended to be used to limit the scope of thereof. Other features, aspects, and elements will be readily apparent to a person skilled in the art in view of this disclosure.

[0005] According to a first aspect, there is provided a method comprising: obtaining, by a user device, a configuration for performing uplink transmissions; and transmitting, by the user device, an uplink signal comprising a plurality of bit sequences based on the configuration, wherein the configuration for performing uplink transmissions comprises: an indication of a mapping for a plurality of uplink transmission powers and a plurality of modulation and coding schemes, wherein an uplink transmission power of the plurality of uplink transmission power pairs with at least one modulation and coding scheme of the plurality of modulation and coding schemes; and / or an indication of one or more bit sequences corresponding to the plurality of bit sequences.

[0006] According to a second aspect, there is provided an apparatus comprising means for performing: obtaining, by a user device, a configuration for performing uplink transmissions; and transmitting, by the user device, an uplink signal comprising a plurality of bit sequencesbased on the configuration, wherein the configuration for performing uplink transmissions comprises: an indication of a mapping for a plurality of uplink transmission powers and a plurality of modulation and coding schemes, wherein an uplink transmission power of the plurality of uplink transmission power pairs with at least one modulation and coding scheme of the plurality of modulation and coding schemes; and / or an indication of one or more bit sequences corresponding to the plurality of bit sequences.

[0007] According to a third aspect, there is provided an apparatus comprising: at least one processor, and at least one memory comprising code that, when executed by the at least one processor, causes the apparatus to perform: obtaining, by a user device, a configuration for performing uplink transmissions; and transmitting, by the user device, an uplink signal comprising a plurality of bit sequences based on the configuration, wherein the configuration for performing uplink transmissions comprises: an indication of a mapping for a plurality of uplink transmission powers and a plurality of modulation and coding schemes, wherein an uplink transmission power of the plurality of uplink transmission power pairs with at least one modulation and coding scheme of the plurality of modulation and coding schemes; and / or an indication of one or more bit sequences corresponding to the plurality of bit sequences.

[0008] According to a fourth aspect, there is provided an apparatus comprising: obtaining circuitry for obtaining, by a user device, a configuration for performing uplink transmissions; and transmitting circuitry for transmitting, by the user device, an uplink signal comprising a plurality of bit sequences based on the configuration, wherein the configuration for performing uplink transmissions comprises: an indication of a mapping for a plurality of uplink transmission powers and a plurality of modulation and coding schemes, wherein an uplink transmission power of the plurality of uplink transmission power pairs with at least one modulation and coding scheme of the plurality of modulation and coding schemes; and / or an indication of one or more bit sequences corresponding to the plurality of bit sequences.

[0009] The following may be applied in respect of any (e.g., one or more, including any) of the above first to fourth aspects.

[0010] The user device may be caused to perform: determining, for each of N downlink signals, a corresponding channel quality metric; and / or providing, to a network access apparatus, an indication of the determined channel quality metrics.

[0011] The N downlink signals may be channel state information reference signals.

[0012] The transmitting, by the user device, the uplink signal comprising the plurality of bit sequences based on the configuration may further comprise: obtaining a set of filter coefficientsfor distorting the uplink signal prior to transmission; and transmitting the uplink signal comprising the plurality of bit sequences based on the set of filter coefficients.

[0013] The transmitting the uplink signal comprising the plurality of bit sequences based on the set of filter coefficients may comprise: preparing the uplink signal comprising the plurality of bit sequences for transmission by convolving a signal obtained based on the configuration for performing uplink transmissions with an emulated channel signal obtained based on the set of filter coefficients.

[0014] The filter coefficients may be obtained based on information indicating at least one of: a type of fading experienced by, or expected to be experienced by, an uplink transmission channel, a doppler shift of the uplink transmission channel, or a power delay profile of the uplink transmission channel.

[0015] The set of filter coefficients may be configured to emulate at least one of: a propagation channel response, or at least one radio frequency imperfection resulting from an expected user handling of the user device.

[0016] The user device may be caused to perform: receiving, by the user device, an indication that uplink link adaptation calibration is being performed or is to be performed by a network access apparatus.

[0017] The user device may be caused to perform: subsequent to said transmitting the uplink signal comprising the plurality of bits: obtaining, by the user device from a network access apparatus, an indication of a selected modulation and coding scheme for performing uplink transmissions across a channel between the user device and the network access apparatus; and transmitting uplink across the channel based on the selected modulation and coding scheme.

[0018] According to a fifth aspect, there is provided a method comprising: transmitting, by a network access apparatus, a configuration for performing uplink transmissions; and receiving, by the network access apparatus, an uplink signal comprising a plurality of bit sequences based on the configuration, wherein the configuration for performing uplink transmissions comprises: an indication of a mapping that defines, for a plurality of uplink transmission powers and a plurality of modulation and coding schemes, wherein an uplink transmission power of the plurality of uplink transmission power pairings with at least one respective modulation and coding scheme of the plurality of modulation and coding schemes; and / or an indication of one or more bit sequences corresponding to the plurality of bit sequences.

[0019] According to a sixth aspect, there is provided an apparatus comprising means for performing: transmitting, by a network access apparatus, a configuration for performing uplink transmissions; and receiving, by the network access apparatus, an uplink signal comprising aplurality of bit sequences based on the configuration, wherein the configuration for performing uplink transmissions comprises: an indication of a mapping that defines, for a plurality of uplink transmission powers and a plurality of modulation and coding schemes, wherein an uplink transmission power of the plurality of uplink transmission power pairings with at least one respective modulation and coding scheme of the plurality of modulation and coding schemes; and / or an indication of one or more bit sequences corresponding to the plurality of bit sequences.

[0020] According to a seventh aspect, there is provided an apparatus comprising: at least one processor, and at least one memory comprising code that, when executed by the at least one processor, causes the apparatus to perform: transmitting, by a network access apparatus, a configuration for performing uplink transmissions; and receiving, by the network access apparatus, an uplink signal comprising a plurality of bit sequences based on the configuration, wherein the configuration for performing uplink transmissions comprises: an indication of a mapping that defines, for a plurality of uplink transmission powers and a plurality of modulation and coding schemes, wherein an uplink transmission power of the plurality of uplink transmission power pairings with at least one respective modulation and coding scheme of the plurality of modulation and coding schemes; and / or an indication of one or more bit sequences corresponding to the plurality of bit sequences.

[0021] According to an eighth aspect, there is provided an apparatus comprising: transmitting circuitry for transmitting, by a network access apparatus, a configuration for performing uplink transmissions; and receiving circuitry for receiving, by the network access apparatus, an uplink signal comprising a plurality of bit sequences based on the configuration, wherein the configuration for performing uplink transmissions comprises: an indication of a mapping that defines, for a plurality of uplink transmission powers and a plurality of modulation and coding schemes, wherein an uplink transmission power of the plurality of uplink transmission power pairings with at least one respective modulation and coding scheme of the plurality of modulation and coding schemes; and / or an indication of one or more bit sequences corresponding to the plurality of bit sequences.

[0022] The following may apply in respect of any (e.g., one or more including all) of the above- mentioned fifth to eighth aspects.

[0023] The network access apparatus may be caused to perform: receiving, by the network access apparatus, an indication of at least one channel quality metric corresponding to a block of N downlink signals.

[0024] The N downlink signals may be channel state information reference signals.

[0025] The network access apparatus may be caused to perform: transmitting the block of N downlink signals by transmitting different downlink signals comprised in said block using a plurality of different transmission powers.

[0026] The network access apparatus may be caused to perform determining the configuration for performing uplink transmissions based on the received indication of at least one channel quality metric corresponding to the block of N downlink channel state information reference signals.

[0027] The network access apparatus may be caused to perform: modifying a preconfigured mapping of signal-to-interference-and-noise ratio to modulation and coding scheme based on a determined at least one channel quality metric corresponding to the received uplink signal to form a modified mapping of signal-to-interference-and-noise ratio to modulation and coding scheme.

[0028] The network access apparatus may be caused to perform: selecting a modulation and coding scheme to be used for signalling across a channel between the user device and the network access apparatus based on a signal-to-interference-and-noise ratio of the channel and the modified mapping of signal-to-interference-and-noise ratio to modulation and coding scheme; and causing the selected modulation and coding scheme to be used for signalling across said channel.

[0029] The network access apparatus may be caused to perform: providing, to the user device, an indication of a set of filter coefficients for distorting the uplink signal prior to transmission.

[0030] The filter coefficients may correspond to at least one of: a type of fading experienced by or expected to be experienced by an uplink transmission channel, a doppler shift of the uplink transmission channel, or a power delay profile of the uplink transmission channel.

[0031] The network access apparatus may be caused to perform: transmitting, by the network access apparatus, an indication that uplink link adaptation calibration is being performed or is to be performed by the network access apparatus.

[0032] According to a ninth aspect, there is provided a method comprising: receiving, by a user device, an indication that triggers uplink link adaptation calibration to be performed; and obtaining, by the user device, a block of N downlink channel state information reference signals for uplink link adaptation calibration based on the indication.

[0033] According to a tenth aspect, there is provided an apparatus comprising means for performing: receiving, by a user device, an indication that triggers uplink link adaptation calibration to be performed; and obtaining, by the user device, a block of N downlink channelstate information reference signals for uplink link adaptation calibration based on the indication.

[0034] According to an eleventh aspect, there is provided an apparatus comprising: at least one processor; and at least one memory comprising code that, when executed by the at least one processor, causes the apparatus to perform: receiving, by a user device, an indication that triggers uplink link adaptation calibration to be performed; and obtaining, by the user device, a block of N downlink channel state information reference signals for uplink link adaptation calibration based on the indication.

[0035] According to a twelfth aspect, there is provided an apparatus comprising: receiving circuitry for receiving, by a user device, an indication that triggers uplink link adaptation calibration to be performed; and obtaining circuitry for obtaining, by the user device, a block of N downlink channel state information reference signals for uplink link adaptation calibration based on the indication.

[0036] The following may apply in respect of any (e.g., one or more, including all) of the above-mentioned ninth to twelfth aspects.

[0037] The user device may be caused to perform: determining, for each of N downlink signals, a corresponding channel quality metric; and / or providing, to a network access apparatus, an indication of the determined channel quality metrics.

[0038] The user device may be caused to perform: obtaining, by the user device, a configuration for performing uplink transmissions; and transmitting, by the user device, an uplink signal comprising a plurality of bit sequences based on the configuration, wherein the configuration for performing uplink transmissions comprises: an indication of a mapping for a plurality of uplink transmission powers and a plurality of modulation and coding schemes, wherein an uplink transmission power of the plurality of uplink transmission power pairs with at least one modulation and coding scheme of the plurality of modulation and coding schemes; and / or an indication of one or more bit sequences corresponding to the plurality of bit sequences.

[0039] The transmitting, by the user device, the uplink signal comprising the plurality of bit sequences based on the configuration may further comprise: obtaining a set of filter coefficients for distorting the uplink signal prior to transmission; and transmitting the uplink signal comprising the plurality of bit sequences based on the set of filter coefficients.

[0040] The transmitting the uplink signal comprising the plurality of bit sequences based on the set of filter coefficients may comprise: preparing the uplink signal comprising the plurality of bit sequences for transmission by convolving a signal obtained based on the configurationfor performing uplink transmissions with an emulated channel signal obtained based on the set of filter coefficients.

[0041] The filter coefficients may be obtained based on information indicating at least one of: a type of fading experienced by, or expected to be experienced by, an uplink transmission channel, a doppler shift of the uplink transmission channel, or a power delay profile of the uplink transmission channel.

[0042] The set of filter coefficients may be configured to emulate at least one of: a propagation channel response, or at least one radio frequency imperfection resulting from an expected user handling of the user device.

[0043] The user device may be caused to perform, subsequent to said transmitting the uplink signal comprising the plurality of bits: obtaining, by the user device from a network access apparatus, an indication of a selected modulation and coding scheme for performing uplink transmissions across a channel between the user device and the network access apparatus; and transmitting uplink across the channel based on the selected modulation and coding scheme.

[0044] The indication that triggers uplink link adaptation calibration to be performed may comprise a predetermined bit having a first value, wherein the absence of the predetermined bit and / or the predetermined bit having a second value indicates that performance of uplink link adaptation calibration is not being triggered to be performed.

[0045] According to a thirteenth aspect, there is provided a method comprising: providing, by a network access apparatus, an indication that triggers uplink link adaptation calibration to be performed; and transmitting, by the network access apparatus, a block of N downlink channel state information reference signals for uplink link adaptation calibration based on the indication.

[0046] According to a fourteenth aspect, there is provided an apparatus comprising means for performing: providing, by a network access apparatus, an indication that triggers uplink link adaptation calibration to be performed; and transmitting, by the network access apparatus, a block of N downlink channel state information reference signals for uplink link adaptation calibration based on the indication.

[0047] According to a fifteenth aspect, there is provided an apparatus comprising: at least one processor; and at least one memory comprising code that, when executed by the at least one processor, causes the apparatus to perform: providing, by a network access apparatus, an indication that triggers uplink link adaptation calibration to be performed; and transmitting, by the network access apparatus, a block of N downlink channel state information reference signals for uplink link adaptation calibration based on the indication.

[0048] According to a sixteenth aspect, there is provided an apparatus comprising: providing circuitry for providing, by a network access apparatus, an indication that triggers uplink link adaptation calibration to be performed; and transmitting circuitry for transmitting, by the network access apparatus, a block of N downlink channel state information reference signals for uplink link adaptation calibration based on the indication.

[0049] The following applies in respect of any (e.g., one or more, including all) of the above- mentioned thirteenth to sixteenth aspects.

[0050] The network access apparatus may be caused to perform: receiving, by the network access apparatus, an indication of at least one channel quality metric corresponding to the block of N downlink channel state information reference signals.

[0051] The transmitting the block of N downlink channel state information reference signals may comprise transmitting different downlink channel state information reference signals comprised in said block using a plurality of different transmission powers.

[0052] The network access apparatus may be caused to perform: transmitting, by a network access apparatus, a configuration for performing uplink transmissions; and receiving, by the network access apparatus, an uplink signal comprising a plurality of bit sequences based on the configuration, wherein the configuration for performing uplink transmissions comprises: an indication of a mapping for a plurality of uplink transmission powers and a plurality of modulation and coding schemes, wherein an uplink transmission power of the plurality of uplink transmission power pairs with at least one modulation and coding scheme of the plurality of modulation and coding schemes; and / or an indication of one or more bit sequences corresponding to the plurality of bit sequences.

[0053] The network access apparatus may be caused to perform: determining the configuration for performing uplink transmissions based on the received indication of at least one channel quality metric corresponding to the block of N downlink channel state information reference signals.

[0054] The network access apparatus may be caused to perform: modifying a preconfigured mapping of signal-to-interference-and-noise ratio to modulation and coding scheme based on a determined at least one channel quality metric corresponding to the received uplink signal to form a modified mapping of signal-to-interference-and-noise ratio to modulation and coding scheme.

[0055] The network access apparatus may be caused to perform: selecting a modulation and coding scheme to be used for signalling across a channel between the user device and the network access apparatus based on a signal-to-interference-and-noise ratio of the channel andthe modified mapping of signal-to-interference-and-noise ratio to modulation and coding scheme; and causing the selected modulation and coding scheme to be used for signalling across said channel.

[0056] The network access apparatus may be caused to perform: providing, to the user device, an indication of a set of filter coefficients for distorting the uplink signal prior to transmission.

[0057] The filter coefficients may correspond to at least one of: a type of fading experienced by or expected to be experienced by an uplink transmission channel, a doppler shift of the uplink transmission channel, or a power delay profile of the uplink transmission channel.

[0058] According to an aspect, there is provided a non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the method according to any of the preceding aspects.

[0059] In the above, many different embodiments have been described. It should be appreciated that further embodiments may be provided by the combination of any two or more of the embodiments described above. DESCRIPTION OF FIGURES

[0060] Some example embodiments will now be described, by way of non-limiting and illustrative example only, with reference to the accompanying Figures in which:

[0061] Figure 1 shows a representation of a radio access network;

[0062] Figure 2 shows a representation of an apparatus for the communication system of Figure 1 according to some example embodiments;

[0063] Figure 3 shows a representation of an apparatus according to some example embodiments;

[0064] Figures 4 and 5 illustrate example signalling between apparatus described herein; and

[0065] Figures 6 to 9 illustrate operations that may be performed by apparatus described herein. DETAILED DESCRIPTION

[0066] In the following various example embodiments are explained with reference to communication devices capable of communication with a communication system. Before explaining in detail the embodiments of the methods and apparatuses of the present disclosure, an access network, network access apparatuses, and communication devices are briefly explained with reference to Figures 1, 2 and 3.

[0067] Figure 1 illustrates an example communication environment in which example embodiments of the present disclosure can be implemented.

[0068] Figure 1 shows an example communication environment 100 in which example embodiments of the present disclosure can be implemented.

[0069] In the communication environment 100, a plurality of communication devices, comprising user devices 110 and 115 (also referred to herein as a “terminal” or “terminal device”) and a network device 120 (also referred to herein as a “network access node” or “network access apparatus”), can communicate with each other. The network device 120 may serve a coverage area, called a cell 125. The user device 110 may have access to a communication network via the cell 125. In some example embodiments, both the user device 110 and the network device 120 may be configured to implement a beamforming technique and communicate with each other via a plurality of beams. The user devices and network devices are illustrated further below with reference to Figures 2 and 3.

[0070] In some example embodiments, a link from the network device 120 to the user device 110 or 115 is referred to as a downlink (DL), while a link from the user device 110 or 115 to the network device 120 is referred to as an uplink (UL). Links are also referred to herein as “channels”. In DL, the network device 120 is a transmitter (Tx) device (or a transmitter), and the user device 110 or 115 is a receiver (Rx) device (or a receiver). In UL, the user device 110 or 115 is a Tx device (or a transmitter), and the network device 120 is a Rx device (or a receiver). A link between the user device 110 and another user device (not shown) is referred to as a sidelink (SL). In SL, one of the user devices is a Tx device (or a transmitter), and the other of the user devices is a Rx device (or a receiver).

[0071] Communications in the communication environment 100 may be implemented according to any proper communication protocol(s), comprising, but not limited to, cellular communication protocols of the first generation (1G), the second generation (2G), the third generation (3G), the fourth generation (4G), the fifth generation (5G), the sixth generation (6G), and the like, wireless local network communication protocols such as Institute for Electrical and Electronics Engineers (IEEE) 802.11 and the like, and / or any other protocols currently known or to be developed in the future. Moreover, the communication may utilize any proper wireless communication technology, comprising but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplex (FDD), Time Division Duplex (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiple (OFDM),Discrete Fourier Transform spread OFDM (DFT-s-OFDM) and / or any other technologies currently known or to be developed in the future.

[0072] As used herein, the term “network device” is used interchangeably with “network access node” and “network access apparatus”, and refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may be as described below with reference to Figure 2.

[0073] Figure 2 illustrates an example of a control apparatus 200 for controlling a function of the access network (e.g., a 5G-RAN or the NG-RAN illustrated in Figure 1) illustrated in Figure 1. The control apparatus 200 may comprise at least one random access memory (RAM) 211a, at least on read only memory (ROM) 211b, at least one processor 212, 213 and a network interface 214. The at least one processor 212, 213 may be coupled to the RAM 211a and the ROM 211b. The at least one processor 212, 213 may be configured to execute an appropriate software code 215. Execution of the software code 215 may for example may cause the apparatus to perform operations for controlling a function of the access network. The software code 215 may be stored in the ROM 211b. The control apparatus 200 may be interconnected with another control apparatus 200 for controlling another function of the 5G-RAN or the NG- RAN. In some embodiments, each function of the 5G-RAN or the NG-RAN is deployed or hosted on a control apparatus 200. In alternative embodiments, two or more functions of the 5G-RAN or the NG-RAN may share a control apparatus.

[0074] The network device may refer to a base station (BS) or an access point (AP), for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), an NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a radio header (RH), a remote radio head (RRH), a relay, an Integrated Access and Backhaul (IAB) node, a low power node such as a femto, a pico, a non-terrestrial network (NTN) or non-ground network device such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, an aircraft network device, and so forth, depending on the applied terminology and technology. In some examples, radio access network (RAN) split architecture comprises a Centralized Unit (CU) and a Distributed Unit (DU) at an IAB donor node. An IAB node comprises a Mobile Terminal (IAB-MT) part that behaves like a UE toward the parent node, and a DU part of an IAB node behaves like a base station toward the next-hop IAB node.

[0075] The term “terminal device” refers to any end device that may be capable of wireless communication. The terminal device may be as described below with reference to Figure 3.

[0076] Figure 3 illustrates an example of a communication device 300, such as the UE illustrated in Figure 1. The communication device 300 may be provided by any device capableof sending and receiving radio signals. The communication device 300 may comprise a transceiver for transmitting and / or receiving, for example, wireless signals carrying communications, for example radio signals. The communications may be one or more of voice, electronic mail (email), text messages, multimedia data, machine data and so on.

[0077] The communication device 300 may receive wireless signals (e.g., radio signals) over an air or radio interface 307 via appropriate apparatus for receiving and may transmit wireless signals via appropriate apparatus for transmitting radio signals. In Figure 3 transceiver is designated schematically by block 306. The transceiver 306 may comprise, for example, a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device and may comprise one or more antenna elements. The antenna arrangement may be a multi-input multi output (MIMO) antenna.

[0078] The communication device 300 may be provided with at least one processor 301, at least one memory ROM 302a, at least one RAM 302b and other possible components 303 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access networks (e.g., the 5G-RAN or NG-RAN illustrated in Figure 1) and other communication devices. The at least one processor 301 is coupled to the RAM 302b and the ROM 302a. The at least one processor 301 may be configured to execute an appropriate software code 308. The software code 308 may for example allow to perform one or more operations of the communication device. The software code 308 may be stored in the ROM 302a.

[0079] The processor, the ROM, and the RAM, the transceiver and other circuitry of the communication device (e.g., a modem) can be provided on a circuit board, in chipsets, or in a system on chip. The circuit board, chipsets or system on chip is denoted by reference 304. The communication device 300 may optionally have a user interface such as key pad 305, touch sensitive screen or pad, combinations thereof or the like. Optionally one or more of a display, a speaker and a microphone may be provided depending on the type of communication device.

[0080] By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), a Portable Subscriber Station, a mobile device, a Mobile Station (MS), or an Access Terminal (AT). The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations,laptop-embedded equipment (LEE), laptop-mounted equipment (LME), USB dongles, smart devices, wireless customer-premises equipment (CPE), a machine-type communications (MTC) device, an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. The terminal device may also correspond to a Mobile Termination (MT) part of an IAB node (e.g., a relay node). In the following description, the terms “terminal device”, “communication device”, “terminal”, “user device”, “user equipment” and “UE” may be used interchangeably.

[0081] The user device is configured to communicate over at least one “link” with a network access node. A link may be considered to be a set of frequency and time resources that can be used for communication. Example links include, for example, physical and / or logical connections between a user device and a network access apparatus.

[0082] Transmissions made over a link between a UE and a network access apparatus can vary in quality based on plurality of variables, including, for example, the instantaneous configuration(s) of the user device and the network access node, the presence of interferers to that link (e.g., buildings, other communication devices, etc.), and / or a relative mobility state between the UE and the network access apparatus. The state of a link between a user device and a network access node may also be labelled as a “channel quality”, with a link that is currently more difficult to receive transmissions accurately on having a worse channel quality than a link that is currently easier to receive transmissions accurately on.

[0083] A channel quality may be measured in any of a plurality of different ways. The method used for measuring channel quality may be selected based on the direction of the link being assessed, the types of signals being transmitted, and the capabilities of the receivers that are measuring the channel quality.

[0084] One example metric that indicates the channel quality is the channel quality indicator (CQI). The CQI is a measure of a downlink signal quality that is determined by a UE. CQI is measured from the reference symbols (e.g., channel state information reference signals) transmitted by network access node. The CQI measurement interval, measurement resolution in frequency domain, reporting mechanisms, etc. are all configurable parameters. Once determined by the UE, the determined CQI may be sent by the UE to the network access node. The determined CQI may comprise a signal-to-interference and noise ratio (SINR) for the measured channel.

[0085] In order to mitigate the effects of varying link conditions in order to enable better reception of transmitted signals, different types of link adaptation (LA) methods have been applied in 3GPP networks. At least one purpose of link adaptation methods is to use feedback information regarding the state of a link (e.g., downlink and / or uplink) to perform the selection of an appropriate modulation and coding scheme (MCS) for that link direction and for that UE.

[0086] For example, in long term evolution (LTE) networks, which utilize a constant downlink transmission power, the type of MCS used for downlink transmission was selected based on a measured downlink channel quality. In more detail, links (e.g., channels) that are measured as having a worse channel quality (e.g., below a predetermined threshold) may be configured to have transmissions made on them using a more robust MCS scheme than those links that are measured as having a better channel quality.

[0087] When the network access node has received and / or has otherwise determined a channel quality metric (e.g., a value indicative of the channel quality), the network node may deploy link adaptation techniques known as Inner Loop Link Adaptation (ILLA) and Outer Loop Link Adaptation (OLLA).

[0088] The ILLA is used to select an MCS to use for transmissions sent to a specific UE. This selection may be based on a measured Signal to Interference plus Noise Ratio (SINR) reported to the network access node in the CQI report. The block error rate (BLER) may also be used as an input to the ILLA algorithm. For example, for the same SINR (e.g. 10 dB), a UE with BLER 10% can be assigned a higher MCS than a UE with a lower BLER (e.g., lower than 10%). There may be ranges of BLER that are paired with respective MCS index values for determining which MCS to use. For example, for the same SINR, a UE with a BLER between 5%-10% can be assigned a higher MCS than a UE with a lower BLER (e.g., lower than 1%- 5%). For example, the access network node may be configured with a mapping that pairs together ranges of SINRs to respective MCS types, such that a value of an SINR may be used to select its respective MCS type according to the configured mapping. This configured mapping between SINR and MCS types may also be referred to as link adaptation (LA) curves, and is mentioned further below.

[0089] In contrast, the OLLA function uses feedback information (e.g., acknowledgements and / or negative acknowledgement information) received from a UE to adapt the SINR that is input to the ILLA for selecting MCS used for downlink transmission. The target of the OLLA function is to adapt the MCS selection to ensure that a certain Block Error Rate (BLER) target is met.

[0090] For example, an OLLA algorithm determines an OLLA offset value based on received acknowledgement data (e.g., ACK / NACK) from a UE. The determined OLLA offset value is subtracted from the received SINR measurements comprised in the CQI for forming adjusted SINR measurements. The adjusted SINR values are then used by the ILLA mechanism with the above-mentioned mapping to determine an MCS value to be used for downlink transmission. Stated differently, the adjusted SINR values are used by the ILLA mechanism instead of the received SINR values when determining an MCS to be used for transmitting on a specific link to a specific UE.

[0091] Thus, in general, when a network device is using a CQI to select the MCS, the process is called ILLA, while the process of selecting the MCS by also using acknowledgements and / or negative acknowledgements of past transmissions is called OLLA. Stated differently, an OLLA scheme uses an acknowledgement scheme (such as the hybrid automatic repeat request (HARQ)) to compensate the CQI inaccuracies reported by UE in downlink link adaptation (or measured by a network apparatus in uplink link adaptation LA) in the MCS selection procedure.

[0092] Current 5G link adaptation comprises configuring an MCS for transmissions using feedback on a channel quality metric sent by the UE to the gNB, and using an MCS index, sent by the gNB to the UE, that maps an MCS index to a modulation and code rate.

[0093] The feedback on the quality of the downlink currently comprises 4 bits and may comprise at least one of Channel State Information (CSI), Channel Quality Indicator (CQI), and / or Signal-to-Interference-and-Noise ratio (SINR). The feedback on the quality of the link may be used by the gNB to select an MCS for a next transmission, including for next uplink transmissions.

[0094] The MCS selected by the gNB may be signalled to the UE by indicating an MCS index that has a value corresponding to the selected MCS. The MCS index is currently signalled using 5 bits. The MCS index table is currently standardized in 3GPP TS 38.214.

[0095] It is therefore understood that current link adaptation in 5G NR systems relies on a network apparatus selecting an MCS based on UE-specific channel information (e.g. CQI, SINR, etc). How the channel quality metric information is used to select the MCS is left to the gNB implementation.

[0096] Stated differently, how the gNB uses the feedback on the quality of the link reported by the UE to select the best MCS is proprietary to a gNB based on its operator. In general, the MCS value selected by a gNB for transmission across a link should be selected with an aim of maximising the throughput of information through the link, while maintaining the BLER belowa certain level. The MCS value selected with this aim in mind is also referred to as a “best” MCS.

[0097] The selection of a “best” MCS often relies on brute-force simulations by the gNB vendor of all the MCS combinations and on obtaining corresponding throughput-v-SINR performance curves in Additive White Gaussian Noise (AWGN) channels. These throughput- v-SINR curves are also called link adaptation curves, as mentioned above. Link adaptation curves can be seen as a mapping between an SINR range and the MCS that provides best throughput. A gNB may use the link adaptation curves, and the reported link feedback information to select an MCS for maximizing the throughput.

[0098] In practice, the selection of a “best” MCS is hard to perform, as a network device performs such a selection based on the most precise and up-to-date information about the channel and interference conditions of the UE available to the network device.

[0099] Moreover, the effects of the UE’s specific power amplifier responses, particularly in the non-linear region, are not accounted for in current models.

[0100] In general, as a signal is passed through a plurality of power amplifiers, the power amplifier outputs may be combined to form an overall output beam shape. Each power amplifier may have a linear mode of operation and a nonlinear mode of operation, and so the output beam shape may comprise both linear and nonlinear parts. The UE may be configured to provide some mechanism for reducing the effects of power amplifier distortions by using at least one of beam shaping techniques and linearization techniques. In particular, the linear part(s) of the beam may be controlled using a calibration process whilst the non-linear part(s) of the beam may be controlled using linearization techniques, such as digital predistortion. The actual operation of the UE may be proprietary, and so vary between UE being served by a single network access device.

[0101] Without getting any feedback from the UE about the response of that UE’s power amplifiers to a received signal, the gNB cannot account for any receiver power amplifier distortion when deriving the link adaptation curves. As a result, a target BLER is seldomly achieved in the field.

[0102] The following aims to address at least one of the above-mentioned issues.

[0103] In particular, the following illustrates at least one method for correcting a link adaptation curve (or table) mapping SINR-to-MCS to compensate for the UE power amplifier distortion in uplink (UL) and downlink, and to especially compensate for the UE’s non-linear power amplifier distortion. The corrected link adaptation curve (or table) may subsequently beused for selecting (and using) a “best” MCS for use in transmissions to and / or from the user equipment. The “best” MCS may be as described above.

[0104] Throughout the following and the above, examples are illustrated for signalling between a UE and a gNB. However, it is understood that these examples are merely for clarity and brevity, and that the actions mentioned below in respect of a gNB may be performed by any network access node (such as a network access node configured according to Figure 1 and Figure 2), and that the actions mentioned below in respect of a UE may be performed in respect of any user device (such as a user device configured according to Figure 1 and Figure 3).

[0105] In the following examples, there is described a gNB that has stored a base (e.g., template and / or default) link adaptation mapping SINR-to-MCS. The base link adaptation mapping SINR-to-MCS may be a link adaptation mapping that would be used for selecting an MCS for a UE to use for uplink transmissions in the event that the presently described method is not deployed.

[0106] The gNB may be configured to select an MCS (also referred to herein as a “best MCS” and / or a “selected MCS”) using this link adaptation mapping and a measured SINR. The selected MCS may be selected for uplink transmission based on an SINR measured on an uplink transmission made by a specific UE.

[0107] In the following examples, the gNB selects N MCS-transmission power pairs to be used for uplink transmission, and provides an indication of these N MCS-transmission power pairs to a UE. Although N may take any integer value in the following examples, N may comprise any integer value in the range of 1 to the number of symbols per slot (which is 14 in current 3GPP specifications). Stated differently, N may take any value from 1 to 14. Further, N may take any value from 2 to 14 when there are a plurality of MCS-transmission power pairs.

[0108] The UE may transmit on these N MCS-transmission power pairs using a NULL transmission (and / or using a preconfigured bit sequence). The gNB may receive the N MCS- transmission power pairs and determine channel quality metrics for those uplink transmissions, such as BLER and / or SINR for the uplink N MCS-transmission power pair transmissions. The determined channel quality metrics may be used by the gNB for selecting an MCS for the UE to use for uplink transmissions.

[0109] The N MCS-transmission power pairs may be selected in any of a plurality of different ways.

[0110] For example, the N MCS-transmission power pairs may be selected using a default set of preconfigured N MCS-transmission power pairs. MCS-transmission power pairs are described further below.

[0111] As another example, the N MCS-transmission power pairs may be selected based on a property of the user device itself (e.g., based on a type or category of UE).

[0112] As another example, the N MCS-transmission power pairs may be selected based on downlink channel quality metric measurements performed by the UE on downlink transmissions made by the gNB. This latter example is illustrated in Figures 4 and 5, below, although it is understood that the presently described techniques may be performed without a UE-specific set of N MCS-transmission power pairs being selected according to the examples of Figures 4 and 5.

[0113] As another example, the N MCS-transmission power pairs may be selected so that a larger number of the N uplink transmissions lie within an expected non-linear region of at least one power amplifier of the UE. Stated differently, the transmission power(s) indicated in the N MCS-transmission power pairs may be selected to be relatively high in the UE’s uplink transmission power range. This may be used to better determine the effects of non-linear power amplifier distortion on the uplink transmissions for adapting an LA curve and / or LA table. It is understood that all of the transmission powers of the N MCS-transmission power pairs may be relatively high in the UE’s uplink transmission power range, or only a subset (e.g., less than all) of the uplink transmission powers of the N MCS-transmission power pairs may be relatively high in the UE’s uplink transmission power range. This latter case may be useful for confirming whether the rest of the LA curve and / or LA table is accurate for linear power amplifier regions of the UE.

[0114] The UE is configured to transmit uplink according to the selected N MCS-transmission power pairs. For example, where N MCS-transmission power pairs MCS-1 / Power1, MCS- 2 / Power2… MCS-N / PowerN are indicated to a UE, the UE transmits uplink according to each of the pairs MCS-1 / Power1, MCS-2 / Power2… MCS-N / PowerN. Stated differently, the UE may transmit a first uplink signal using MCS-1 at Power1, a second uplink signal using MCS- 2 at Power2, and so on until the Nth uplink signal is transmitted using MCS-N at Power N.

[0115] These N uplink transmissions may be a so-called “mock” transmission in which the UE sends a predetermined bit vector per transmission. Stated differently, the UE may be configured to transmit at least one preconfigured bit sequence on these N uplink transmissions. The at least one preconfigured bit sequence may correspond to a NULL transmission. The at least one preconfigured bit sequence may be configured by the gNB. The at least one preconfigured bit sequence may be configured according to a governing 3GPP standard. The at least one preconfigured bit sequence may be selected in order to enable the gNB to compute anachievable block error rate (BLER) from measurements performed on the N uplink transmissions.

[0116] For each of these N transmissions, the gNB determines a corresponding BLER for that uplink transmission. At the end of N transmissions, the gNB has N BLER measurements that may be used by the gNB for adapting the base link adaptation mapping SINR-to-MCS to obtain an adapted mapping SINR-to-MCS that is specific to that UE, including that UE’s power amplifier distortion. The adapted mapping SINR-to-MCS may be used by the gNB and / or the UE for selecting MCS for use by the UE when the UE transmits uplink.

[0117] Stated differently, the UE transmits uplink according to its configuration, and the gNB decodes this uplink transmission and computes an empirical SINR-block eror rate (BLER) throughput unique to that UE. Using the empirical SINR-BLER metrics, the gNB corrects the base link adaptation SINR-to-MCS mapping to form the adapted mapping SINR-to-MCS. For example, the gNB may change the SINR ranges for each MCS and generate a corrected link adaptation SINR-to-MCS mapping.

[0118] The presently described techniques are further illustrated with respect to Figures 4 to 9. It is therefore understood that the above-described features may find corresponding functionality with features described below in the examples of Figures 4 and 9.

[0119] The examples of Figures 4 and 5 relate to situations in which a gNB uses channel quality metric information obtained by a UE on downlink signals in order to select N MCS- transmission power pairs for use by the UE in transmitting uplink. It is understood that this is merely an example, and that the N MCS-transmission power pairs may be selected by the gNB without such channel quality metric information. However, the use of such channel quality metrics for the N downlink signals may be useful for identifying a potential non-linear region of the UE’s power amplifiers. This information may thus be used for selecting which MCS- transmission power pairs are to be used for uplink transmissions.

[0120] It is further understood that although the following examples use the same number of downlink and uplink signals (N), that this is merely an example, and that different numbers of downlink signals may be used relative to the number of uplink signals (e.g., N downlink signals may be used in 4002 and / or 5002, and M uplink signals may be used in 4008 and / or 5009, where N is different to M). Similar to the above description of N (which also applies in respect of Figures 4 to 9), although M may take any integer value in the following examples, M may comprise any integer value in the range of 1 to the number of symbols per slot (which is 14 in current 3GPP specifications). Stated differently, M may take any value from 1 to 14. Further,M may take any value from 2 to 14 when there are a plurality of MCS-transmission power pairs.

[0121] It is further understood that 4001 and 5001 may be optional in the following. The performance of 4001 and 5001 may be useful, however, in indicating to the UE what measurements are to be performed on the incoming N downlink signals and what CQM are to be reported on these N downlink signals.

[0122] A first example is illustrated in Figure 4.

[0123] Figure 4 illustrates signalling that may be performed between a UE 401 and a gNB 402.

[0124] During 4001, the gNB 402 signals the UE 401. This signalling may comprise a value that triggers an uplink link adaptation calibration method to be performed. This signalling may be as described below in relation to Figures 6 to 9.

[0125] 4002 to 4004 relate to the emulation of multiple downlink SINR regimes.

[0126] During 4002, the gNB 402 signals the UE 401. This signalling may comprise a block of N downlink channel state information reference signals (CSI-RS) that are each transmitted using a different transmission power for at least two of the N CSI RS. In an example, each CSI RS in the block of N CSI RS are transmitted using a different transmission power to all other CSI RS in the block of N CSI RS. In an example, each CSI-RS in the block of N CSI-RS is transmitted using a first transmission power, where the first transmission power is a higher transmission power than the transmission power used to transmit an immediately adjacent CSI- RS and where the first transmission power is also a lower transmission power than the transmission power used to transmit another immediately adjacent CSI-RS. Stated differently, the gNB 402 may transmit a block of N CSI-RS with increasing transmission power T1, …, TN, where TN is the maximum transmit power. The transmission powers T1 to TN may emulate different downlink SINR regimes at the UE.

[0127] During 4003, the UE determines (e.g., computes) a downlink channel quality metric (CQM) associated with each of the N CSI-RS. In the following, CQM_1 will represent the CQM associated with the CSI RS that was transmitted using transmission power T1, CQM_2 will represent the CQM associated with the CSI RS that was transmitted using transmission power T2, and so on until CQM_N represents the CQM associated with the CSI RS that was transmitted using transmission power TN. The CQM may be at least one of SINR, CQI, or CSI.

[0128] During 4004, the UE 401 signals the gNB 402. This signalling may comprise the determined channel quality metrics of 4003.

[0129] 4005 to 4008 relate to the emulation of multiple uplink SINR regimes.

[0130] During 4005, the gNB 402 uses the received CQM from 4004 to determine N MSC and N transmission power uplink configuration for use by the UE in transmitting uplink. The uplink configuration may be used for serving as calibration of the LA curves.

[0131] Stated differently, the gNB obtains a UE uplink configuration for causing the UE to perform at least N UL transmissions based on the N different downlink SINR regimes experienced by the UE, each UE uplink configuration comprising corresponding pairs of an MCS index and an uplink transmission power (e.g., an MCS1-P1 pair, an MCS2-P2 pair… an MCSN-PN pair). Further, the MCS1-P1 pair may correspond to CQM_1, the MCS2-P2 pair may correspond to CQM_2, and so forth.

[0132] It is understood that although the combination of each MCSx-Px is different to every other MCS-transmission power pair in the UE uplink configuration, that the same MCS and / or transmission power may be the same across different pairs. For example, MCS1 and MCS2 may be the same while P1 and P2 are different, or MCS1 and MCS2 may be different while P1 and P2 are the same, or MCS1 and MCS2 may be different while P1 and P2 are different.

[0133] During 4006, the gNB 402 signals the UE 401. This signalling may comprise he configuration determined during 4005. This signalling may comprise a configuration of at least one uplink bit sequence to be used for performing the signalling of 4007 to 4008.

[0134] The at least one uplink bit sequence may be unique per MCS-power pair. This may be useful for enabling the receiving gNB 402 to identify which uplink transmission belongs to which MCS-power pair.

[0135] The at least one uplink bit sequence may be the same for two or more MCS-power pairs. For example, there may be a first uplink bit sequence that corresponds to a first uplink transmission power, such that all MCS-power pairs that comprise that first uplink transmission power are transmitted using the first uplink bit sequence, a second uplink bit sequence that corresponds to a second uplink transmission power, such that all MCS-power pairs that comprise that second uplink transmission power are transmitted using the second uplink bit sequence, and so on. The first uplink bit sequence is different to the second uplink bit sequence, the first uplink transmission power is different to the second uplink transmission power, and so on.

[0136] The at least one uplink bit sequence may be the same for all MCS-pairs. This may be useful when the UE 401 is making other uplink transmissions (e.g., uplink data transmissions) while performing the uplink transmissions according to the configuration of 4006.

[0137] During 4007, the UE 401 prepares to make uplink transmissions in accordance with (e.g., based on and / or using) the configuration received during 4006. Stated differently, during4007, the UE 401 prepares to make uplink transmissions based on the configuration received during 4006. This preparation may comprise amplifying the transmission power to include a power amplifier distortion effect. Stated differently, at least some of the transmission powers comprised in the configuration received during 4006 may cause the UE 401 to transmit uplink using a power that brings at least one of the UE’s power amplifiers into its nonlinear region.

[0138] During 4008, the UE 401 transmits uplink in accordance with the configuration received during 4006. Stated differently, the UE makes a block of N uplink transmissions, each of the uplink transmissions corresponding to a respective MCS-power pair (e.g., MCS1-P1, MCS2-P2… MCSN-PN).

[0139] During 4009, the gNB 402 measures the UL SINR and the BLER of the uplink signals transmitted during 4008 to obtain an empirical BLER-SINR relationship. The gNB 402 uses the empirical BLER-SINR relationship obtained from these measurements to adjust a preconfigured default link adaptation curve that corresponds to a baseline BLER to SINR mapping.

[0140] It is understood that Figure 4 is merely an example and that at least one step of Figure 4 may be omitted or modified and still be able to provide a recalibration of a baseline BLER to SINR mapping.

[0141] For example, during 4001, the gNB triggers UL LA calibration separately from the transmission of N downlink CSI-RS during 4002. However, the signalling of 4001 may be omitted, and the UE may instead be configured to obtain CQM for any CSI-RS that it receives from the gNB, regardless of whether they are transmitted singly or as a block of increasing transmission power. Stated differently, the presently described procedure may be performed transparently to the UE (e.g., the UE may not be aware that the gNB is recalibrating its BLER- uplink SINR link adaptation curve.

[0142] In a further variation, instead of transmitting a block of N downlink CSI-RS with differing power during 4002, the gNB may instead transmit a single first CSI-RS at a first power, receive from the UE the computed CQM of 4003 for that single first CSI-RS during 4004, and repeat 4002 to 4004 at separate times for each single CSI-RS.

[0143] Stated differently, the gNB may trigger a single CSI-RS transmission at full power and configure a single uplink transmission at a time, and thus repeat the procedure until all downlink SINR regimes have been observed by the UE, and until all MCS points have been configured for the subsequent uplink transmissions.

[0144] A further variation to the example of Figure 4 is shown in Figure 5. In this variation to the example of Figure 4, for the emulation of the uplink SINR regime, the UE is configured toconvolve the uplink signal with an emulated channel g(j) that represents a channel distortion in order to mimic changing channel conditions.

[0145] Stated differently, the gNB of Figure 5 may configure the UE to prepare the UL transmission block to be transmitted by the UE using (e.g., based on) an additional pre- distortion effect to emulate various channel responses. The information obtained from the channel metrics obtained on such uplink signalling may be used by the gNB to additionally tune the link adaptation curves / link adaptation mapping to account for channel fading effects.

[0146] Therefore, in Figure 4, the UE prepares a transmit signal s(t) for uplink transmission, which is then distorted by the UE’s power amplifiers to form signal v(t). Signal v(t) before being sent over the wireless propagation channel h(t). This means that, in the example of Figure 4, the gNB ultimately observes the signal (v(t)*h(t)),

[0147] In contrast, in the example of Figure 5, the UE is configured to send a signal (v(t)*g(j(t))) over the wireless propagation channel h(t), where j = 1:J, and where g(j(t)) emulates a wireless propagation channel response. Consequently, in the example of Figure 5, the gNB will ultimately receive a signal (v(t)*g(j(t))*h(t)).

[0148] Figure 5 illustrates signalling that may be performed between a UE 501 and a gNB 502. 5001 to 5005 may correspond to 4001 to 4005 (e.g., 5001 may be optional, and / or 5002 to 5004 may be performed based on a block of downlink CSI-RS, or on a plurality of single CSI-RS transmissions).

[0149] During 5001, the gNB 502 signals the UE 501. This signalling may comprise a value that triggers an uplink link adaptation calibration method to be performed.

[0150] 5002 to 5004 relate to the emulation of multiple downlink SINR regimes.

[0151] During 5002, the gNB 502 signals the UE 501. This signalling may comprise a block of N downlink channel state information reference signals (CSI-RS) that are each transmitted using a different transmission power for at least two of the N CSI RS. In an example, each CSI RS in the block of N CSI RS are transmitted using a different transmission power to all other CSI RS in the block of N CSI RS. In an example, each CSI-RS in the block of N CSI-RS is transmitted using a first transmission power, where the first transmission power is a higher transmission power than the transmission power used to transmit an immediately adjacent CSI- RS and where the first transmission power is also a lower transmission power than the transmission power used to transmit another immediately adjacent CSI-RS. Stated differently, the gNB 502 may transmit a block of N CSI-RS with increasing transmission power T1, …, TN, where TN is the maximum transmit power. The transmission powers T1 to TN may emulate different downlink SINR regimes at the UE.

[0152] During 5003, the UE determines (e.g., computes) a downlink channel quality metric (CQM) associated with each of the N CSI-RS. In the following, CQM_1 will represent the CQM associated with the CSI RS that was transmitted using transmission power T1, CQM_2 will represent the CQM associated with the CSI RS that was transmitted using transmission power T2, and so on until CQM_N represents the CQM associated with the CSI RS that was transmitted using transmission power TN. The CQM may be at least one of SINR, CQI, or CSI.

[0153] During 5004, the UE 501 signals the gNB 502. This signalling may comprise the determined channel quality metrics of 5003.

[0154] 5005 to 5008 relate to the emulation of multiple uplink SINR regimes.

[0155] During 5005, the gNB 502 uses the received CQM from 5004 to determine N MSC and N transmission power uplink configuration for use by the UE in transmitting uplink. The uplink configuration may be used for serving as calibration of the LA curves.

[0156] Stated differently, the gNB obtains a UE uplink configuration for causing the UE to perform at least N UL transmissions based on the N different downlink SINR regimes experienced by the UE, each UE uplink configuration comprising corresponding pairs of an MCS index and an uplink transmission power (e.g., an MCS1-P1 pair, an MCS2-P2 pair… an MCSN-PN pair). Further, the MCS1-P1 pair may correspond to CQM_1, the MCS2-P2 pair may correspond to CQM_2, and so forth.

[0157] It is understood that although the combination of each MCSx-Px is different to every other MCS-transmission power pair in the UE uplink configuration, that the same MCS and / or transmission power may be the same across different pairs. For example, MCS1 and MCS2 may be the same while P1 and P2 are different, or MCS1 and MCS2 may be different while P1 and P2 are the same, or MCS1 and MCS2 may be different while P1 and P2 are different.

[0158] During 5006, the gNB 502 signals the UE 501. This signalling may comprise he configuration determined during 5005. This signalling may comprise a configuration of the uplink bit sequences.

[0159] The at least one uplink bit sequence may be unique per MCS-power pair. This may be useful for enabling the receiving gNB 502 to identify which uplink transmission belongs to which MCS-power pair.

[0160] The at least one uplink bit sequence may be the same for two or more MCS-power pairs. For example, there may be a first uplink bit sequence that corresponds to a first uplink transmission power, such that all MCS-power pairs that comprise that first uplink transmission power are transmitted using the first uplink bit sequence, a second uplink bit sequence that corresponds to a second uplink transmission power, such that all MCS-power pairs thatcomprise that second uplink transmission power are transmitted using the second uplink bit sequence, and so on. The first uplink bit sequence is different to the second uplink bit sequence, the first uplink transmission power is different to the second uplink transmission power, and so on.

[0161] The at least one uplink bit sequence may be the same for all MCS-pairs. This may be useful when the UE 501 is making other uplink transmissions (e.g., uplink data transmissions) while performing the uplink transmissions according to the configuration of 5006.

[0162] This signalling of 5006 may further comprise a channel emulation distortion g(j(t)), where j=1,…,J. The channel emulation distortion may be represented at least one filter coefficient that may be used by the UE 501 for emulating the effect of changing channel conditions over time. The channel distortion being emulated by g(j(t)) may comprise any changing channel effect, such as, for example, a type of fading (e.g., Rayleigh fading, Rician fading, etc.), a power delay profile (e.g., such as defined in 3GPP TS 39.901), and / or a Doppler shift. Information indicating which channel distortion effect(s) is / are to be emulated may be indicated by the gNB to the UE 501 during 5006. It is understood that this signalling of 5006 may comprise information for enabling the UE 501 to generate the channel emulation distortion g(j(t)) to be applied during 5008.

[0163] During 5007, the UE 501 prepares to make uplink transmissions in accordance with the configuration received during 5006. Stated differently, during 5007, the UE 501 prepares to make uplink transmissions based on the configuration received during 5006. This preparation may comprise amplifying the transmission to include a power amplifier distortion effect.

[0164] During 5008, the UE convolves the prepared uplink transmission with the emulated channel g(j).

[0165] During 5009, the UE 501 transmits uplink in accordance with the configuration received during 5006. Stated differently, the UE makes a block of N uplink transmissions, each of the uplink transmissions corresponding to a respective MCS-power pair (e.g., MCS1-P1, MCS2-P2… MCSN-PN).

[0166] During 5010, the gNB 502 measures the UL SINR and the BLER of the uplink signals transmitted during 5008 to obtain an empirical BLER-SINR relationship. The gNB 502 uses the empirical BLER-SINR relationship obtained from these measurements to adjust a preconfigured default link adaptation curve that corresponds to a baseline BLER to SINR mapping.

[0167] It is understood in the above examples of Figures 4 and 5 that even if the UE applies a digital predistortion (DPD) method for compensating for nonlinear effects of power amplifiersaturation distortion, this DPD method typically does not fully compensate for the distortion, and so the presently applied techniques may further be useful.

[0168] It is further understood that when the UE of Figure 4 and / or Figure 5 is configured to perform an adaptive DPD method for compensating for digital predistortion effects, the UE may inform the gNB of this DPD method usage. Subsequently, the gNB may relax the frequency of its own uplink link adaptation curve (e.g., mapping) calibration procedure such that it is performed less frequently for UEs that are performing such DPD methods that it is for UEs that are not performing such DPD methods.

[0169] It is further understood that although the above described methods may be configured so that the UE performs uplink transmissions across a range of different uplink transmission powers, there may be an especially useful effect by configuring the UE to perform the majority of those uplink transmissions at higher transmission powers (e.g., in those transmission power regions in which the UE is more likely to experience non-linear power amplifier distortion).

[0170] Stated differently, the gNB may select at the uplink transmission powers during 4005 and / or 5005 by identifying a range of uplink transmission powers for that UE that corresponds to a non-linear power amplifier distortion region, and select uplink transmission powers for the configuration signalled during 4006 and / or 5006 such that a majority (e.g., more than half, up to all) of the uplink transmission powers in the configuration signalled are within the identifier range of uplink transmission power. The range of uplink transmission power may correspond to a predetermined range that is common to a plurality of UE, or may correspond to a UE- specific range that is determined based on previous measurements of uplink transmissions. It is further understood that where the above described methods of Figures 4 and 5 are repeated (e.g., to update the link adaptation mapping for a UE to be reflective of current channel conditions), the second and further repeats of this method may increase the proportion of uplink transmissions made using uplink transmission powers in the range of uplink transmission powers relative to total uplink transmissions made, compared to ratios used in the first execution of this method.

[0171] At least some of the above-mentioned features are illustrated below with reference to Figures 6 to 9, which highlight features that may be performed by apparatus described herein. It is therefore understood that at least some of the following features may functionally correspond to at least one feature mentioned above. Further, it is understood that at least one of the following features may be further understood with reference to the above examples.

[0172] Figures 6 and 7 illustrate features that may be performed by interacting apparatus.

[0173] Figure 6 illustrates operations that may be performed by an apparatus. The apparatus may be an apparatus of a user device. Stated differently, the features described below in relation in Figure 6 may appear to be performed by a user device. The user device may be a communication device, as described above in relation to Figure 3. For example, the apparatus may be an apparatus of a terminal, and / or user equipment, or the like.

[0174] During 601, the apparatus obtains a configuration for performing uplink transmissions.

[0175] The apparatus may obtain the configuration in a plurality of different ways. For example, the configuration may be at least partly provided via signalling received from a network apparatus (e.g., a network access apparatus, such as described below in relation to Figures 7 and / or 9, and / or from a network function), or via preconfiguration at the apparatus by an operator. It is further understood that the configuration may be provided wholly by one of these options, or partially by one of these options (e.g., less than all).

[0176] During 602, the apparatus transmits an uplink signal comprising a plurality of bit sequences based on the configuration. In the present instance, “based on the configuration” may be understood as meaning “in accordance with the configuration” and / or “compliant with the configuration”.

[0177] The configuration for performing uplink transmissions may comprise at least one of: an indication of a mapping for a plurality of uplink transmission powers and a plurality of modulation and coding schemes, wherein an uplink transmission power of the plurality of uplink transmission power pairs with at least one modulation and coding scheme of the plurality of modulation and coding schemes; and / or an indication of one or more bit sequences corresponding to the plurality of bit sequences.

[0178] It is understood that the configuration may be provided to the apparatus at a single time, or at different times. For example, the indication of the mapping and the indication of the one or more bit sequences may both be provided at a same, first time (e.g., as part of a same signalling operation). As another example, the indication of the mapping may be provided at a first time, and the one or more bit sequences may be provided at a second time that is at a different time (e.g., as part of different signalling operations).

[0179] The indication(s) may comprise the information itself, and / or a reference for obtaining the information, and / or data for obtaining the information.

[0180] For example, the indication of the mapping for a plurality of uplink transmission powers and a plurality of modulation and coding schemes may comprise the mapping itself, an index for identifying the uplink transmission powers and the plurality of modulation coding schemes (e.g., by identifying a subset of uplink transmission powers out of a larger number of uplinktransmission powers, and / or by identifying a subset of MCS out of a larger number of MCS), and / or some other value (e.g., a measurement value) that may be used from selecting the plurality of uplink transmission powers and / or the plurality of MCS from a larger pool (e.g., number) of uplink transmission powers and / or MCS.

[0181] The apparatus may determine, for each of N downlink signals, a corresponding channel quality metric; and / or provide, to a network access apparatus, an indication of the determined channel quality metrics. For example, the apparatus of Figure 6 may receive, from a network access apparatus (such as described in relation to the apparatus of Figure 7 and / or Figure 9), N downlink signals, perform measurements on those N downlink signals for computing (e.g., determining) channel quality metrics that represent a state of the N downlink signals, and, after computing the channel quality metrics, provide the channel quality metrics (or at least one value representing and / or reflecting the channel quality metrics) to the network access apparatus.

[0182] The channel quality metrics may comprise, for example, a signal-to-interference-and- noise ratio (or similar) for one or more (e.g., all or less than all, including more than one) of the N downlink signals.

[0183] It is understood that any reference in relation to Figure 6 to a network access apparatus may correspond to the network access apparatus of Figure 7 and / or Figure 9.

[0184] The N downlink signals may comprise N downlink reference signals. The N downlink signals may comprise N channel state information reference signals. The N downlink signals may be received before the above-mentioned obtaining of 601.

[0185] The transmitting, by the user device, the uplink signal comprising the plurality of bit sequences based on (e.g., using) the configuration may comprise obtaining a set of filter coefficients for distorting the uplink signal prior to transmission, and transmitting the uplink signal comprising the plurality of bit sequences based on (e.g., using) the set of filter coefficients.

[0186] The filter coefficients may be values that may be used for obtaining g(j(t)), as described above. Stated differently, the transmitting the uplink signal comprising the plurality of bit sequences based on the set of filter coefficients may comprise preparing the uplink signal comprising the plurality of bit sequences for transmission by convolving a signal obtained based on (e.g., using) the configuration for performing uplink transmissions with an emulated channel signal obtained based on (e.g., using) the set of filter coefficients.

[0187] The obtaining may be performed in any of a plurality of different ways. For example, the obtaining may be performed, at least in part, by receiving one or more (including all) of thefilter coefficients in the set of filter coefficients from the network access apparatus. As another example, the obtaining may be performed, at least in part, by computing one or more (including all) of the filter coefficients in the set of filter coefficients from at least one or measurements performed by the user device or from values (e.g., measurement values and / or parameter values) provided by the network access apparatus.

[0188] The filter coefficients may be obtained based on (e.g., using) information indicating at least one of: a type of fading experienced by, or expected to be experienced by, an uplink transmission channel, a doppler shift of the uplink transmission channel, or a power delay profile of the uplink transmission channel. This information may be preconfigured at the user device, or signalled dynamically from a network access apparatus.

[0189] The set of filter coefficients may be configured to emulate at least one of: a propagation channel response, or at least one radio frequency imperfection resulting from an expected user handling of the user device.

[0190] The apparatus may receive an indication that uplink link adaptation calibration is being performed or is to be performed by a network access apparatus. The indication may be received before the above-mentioned obtaining of 601. The indication may be an explicit indication. For example, the indication may be expressed as a predetermined bit value in a designated field, where the absence of the designated field and / or a different bit value in the designated field from the predetermined bit value indicates that uplink link adaptation calibration is not being performed or will not be performed by the network access apparatus.

[0191] Subsequent to said transmitting the uplink signal comprising the plurality of bit sequences, the apparatus may obtain, from a network access apparatus, an indication of a selected modulation and coding scheme for performing uplink transmissions across a channel between the user device and the network access apparatus, and transmit uplink across the channel based on (e.g., using) the selected modulation and coding scheme.

[0192] The indicated selected modulation and coding scheme may have been determined based on the uplink signal comprising the plurality of bit sequences, and so may be said to be based on the uplink signal comprising the plurality of bit sequences. For example, the network access apparatus may be configured to receive the uplink signal comprising the plurality of bit sequences and perform measurements thereon, and use the measurements for adapting the method used for selecting an MCS for uplink transmission, and / or for adapting the LA curve / mapping used for selecting the MCS for uplink transmission. The adapted method and / or LA mapping may be subsequently used for selecting an MCS, which is subsequently indicatedto the user device. The user device uses this indicated selected MCS for uplink transmission. This is further discussed in relation to Figure 7.

[0193] Figure 7 illustrates operations that may be performed by an apparatus of a network access apparatus. The network access apparatus may be as described above in relation to Figure 2. The network access apparatus may comprise a network access node, such as a gNB, base station, etc. The network access apparatus of Figure 7 may correspond to the network access apparatus discussed in relation to the apparatus of Figure 6.

[0194] During 701, the apparatus transmits a configuration for performing uplink transmissions. This configuration may be as described above in relation to the obtaining of the configuration during 601.

[0195] During 702, the apparatus receives, an uplink signal comprising a plurality of bit sequences based on the configuration. This uplink signal may be as described above in relation to 602.

[0196] The configuration for performing uplink transmissions may comprise at least one of: an indication of a mapping for a plurality of uplink transmission powers and a plurality of modulation and coding schemes, wherein an uplink transmission power of the plurality of uplink transmission power pairs with at least one modulation and coding scheme of the plurality of modulation and coding schemes; and / or an indication of one or more bit sequences corresponding to the plurality of bit sequences.

[0197] It is understood that the configuration may be provided to the apparatus at a single time, or at different times. For example, the indication of the mapping and the indication of the one or more bit sequences may both be provided at a same, first time (e.g., as part of a same signalling operation). As another example, the indication of the mapping may be provided at a first time, and the one or more bit sequences may be provided at a second time that is at a different time (e.g., as part of different signalling operations).

[0198] The indication(s) may comprise the information itself, and / or a reference for obtaining the information, and / or data for obtaining the information.

[0199] For example, the indication of the mapping for a plurality of uplink transmission powers and a plurality of modulation and coding schemes may comprise the mapping itself, an index for identifying the uplink transmission powers and the plurality of modulation coding schemes (e.g., by identifying a subset of uplink transmission powers out of a larger number of uplink transmission powers, and / or by identifying a subset of MCS out of a larger number of MCS), and / or some other value (e.g., a measurement value) that may be used from selecting theplurality of uplink transmission powers and / or the plurality of MCS from a larger pool (e.g., number) of uplink transmission powers and / or MCS.

[0200] The apparatus may receive an indication of at least one channel quality metric corresponding to a block of N downlink signals. The N downlink signals may comprise reference signals. The N downlink signals may comprise CSI reference signals.

[0201] The N downlink signals may comprise N downlink signals transmitted by the apparatus. The apparatus may transmit the block of N downlink signals by transmitting different downlink signals comprised in said block using a plurality of different transmission powers.

[0202] The apparatus may determine the configuration for performing uplink transmissions based on (e.g., using) the received indication of at least one channel quality metric corresponding to the block of N downlink signals. The at least one channel quality metric may be as described above in relation to Figure 6. The channel quality metrics may comprise, for example, a signal-to-interference-and-noise ratio (or similar) for one or more (e.g., all or less than all, including more than one) of the N downlink signals.

[0203] The apparatus may modify a preconfigured mapping of signal-to-interference-and- noise ratio to modulation and coding scheme based on a determined at least one channel quality metric corresponding to the received uplink signal to form a modified mapping of signal-to- interference-and-noise ratio to modulation and coding scheme.

[0204] The preconfigured mapping may be preconfigured in any of a plurality of different ways.

[0205] For example, the preconfigured mapping may correspond to at least one default (or template) LA mapping available to the network access node for use by the network access node for selecting an MCS for a UE when the LA mapping is not to be modified.

[0206] As another example, the preconfigured mapping may correspond to a previously obtained LA mapping that was uniquely used for the user device.

[0207] Further, the modification of the preconfigured mapping may correspond to a modification of the method of selecting an MCS from a LA mapping (e.g., link adaptation curve) and / or to a modification of the LA mapping itself (e.g., so that at least one SINR in the modified LA mapping corresponds to a different MCS than would be obtained using the unmodified LA mapping). In general, the modification of the preconfigured mapping may be said to result in at least one SINR corresponding to a different MCS than would be obtained prior to modification of the preconfigured mapping.

[0208] The apparatus may select a modulation and coding scheme to be used for signalling across a channel between the user device and the network access apparatus based on (e.g.,using) a signal-to-interference-and-noise ratio of the channel (which may be obtained based on a measured BLER, as described above) and the modified mapping of signal-to-interference- and-noise ratio to modulation and coding scheme, and cause the selected modulation and coding scheme to be used for signalling across said channel. The apparatus may subsequently receive uplink signals from the user device across that channel using the selected MCS.

[0209] The apparatus may provide, to the user device, an indication of a set of filter coefficients for distorting the uplink signal prior to transmission.

[0210] The filter coefficients may be values that may be used for obtaining g(j(t)), as described above.

[0211] The providing may be performed in any of a plurality of different ways. For example, the apparatus may transmit one or more (including all) of the filter coefficients in the set of filter coefficients to the user device. As another example, the providing may comprise, at least in part, providing values (e.g., measurement values and / or parameter values) that may be used by the user device with other information to compute the set of filter coefficients.

[0212] The filter coefficients may be based on (e.g., obtained using) information indicating at least one of: a type of fading experienced by, or expected to be experienced by, an uplink transmission channel, a doppler shift of the uplink transmission channel, or a power delay profile of the uplink transmission channel. For example, the apparatus may estimate a type of channel interference experienced by the channel for which the MCS is to be selected based on historical measurement data of that channel, and / or by assuming that the uplink channel will have a similar response as the downlink channel and using this assumption and the channel quality metrics previously indicated by the user device to determine how transmissions the uplink transmission channel will be affected.

[0213] The set of filter coefficients may be selected by the apparatus with an aim of emulating at least one of: a propagation channel response, or at least one radio frequency imperfection resulting from an expected user handling of the user device. For example, the network access apparatus may estimate (e.g., based on historical channel information between the user device and the network access apparatus and / or channel information between at least one other user device and the network access apparatus, and / or preconfigured filter coefficient combinations) a channel response to an uplink transmission made by the user device across a cannel, and select the set of filter coefficients using (e.g., based on) the estimated channel response so as to emulate said estimated channel response.

[0214] The apparatus may transmit, to the user device, an indication that uplink link adaptation calibration is being performed or is to be performed by the network access apparatus. Theindication may be received before the above-mentioned obtaining of 601. The indication may be an explicit indication. For example, the indication may be expressed as a predetermined bit value in a designated field, where the absence of the designated field and / or a different bit value in the designated field from the predetermined bit value indicates that uplink link adaptation calibration is not being performed or will not be performed by the network access apparatus.

[0215] Figures 8 and 9 illustrate another example of interacting apparatus. It is understood that at least some of the features below are as described above in relation to Figures 6 and / or 7 where the same or corresponding language is used.

[0216] Figure 8 illustrates a method that may be performed by an apparatus for a user device. The user device may be a communication device as described above in relation to Figure 3.

[0217] During 801, the apparatus receives an indication that triggers uplink link adaptation calibration to be performed. The indication may be received from a network access apparatus, such as the network access apparatus of Figure 9, and / or Figure 7.

[0218] The indication may be an explicit indication. For example, the indication may be expressed as a predetermined bit value in a designated field, where the absence of the designated field and / or a different bit value in the designated field from the predetermined bit value indicates that uplink link adaptation calibration is not being performed or will not be performed by the network access apparatus.

[0219] Stated differently, the indication that triggers uplink link adaptation calibration to be performed comprises a predetermined bit having a first value, wherein the absence of the predetermined bit and / or the predetermined bit having a second value indicates that performance of uplink link adaptation calibration is not being triggered to be performed.

[0220] During 802, the apparatus obtains a block of N downlink channel state information reference signals for uplink link adaptation calibration based on the indication. The obtaining of 802 may comprise receiving N downlink CSI reference signals.

[0221] It is understood that the N downlink CSI reference signals may be substituted by any N downlink signals, including N downlink reference signals. The N downlink signals may comprise a preconfigured form and / or bit sequences.

[0222] The apparatus may determine for each of the N downlink signals, a corresponding channel quality metric, and / or provide, to a network access apparatus, an indication of the determined channel quality metrics.

[0223] The apparatus may obtain a configuration for performing uplink transmissions; and transmit an uplink signal comprising a plurality of bit sequences based on the configuration, wherein the configuration for performing uplink transmissions comprises: an indication of amapping for a plurality of uplink transmission powers and a plurality of modulation and coding schemes, wherein an uplink transmission power of the plurality of uplink transmission power pairs with at least one modulation and coding scheme of the plurality of modulation and coding schemes; and / or an indication of one or more bit sequences corresponding to the plurality of bit sequences.

[0224] The transmitting the uplink signal comprising the plurality of bit sequences based on the configuration may further comprise: obtaining a set of filter coefficients for distorting the uplink signal prior to transmission; and transmitting the uplink signal comprising the plurality of bit sequences based on the set of filter coefficients.

[0225] The transmitting the uplink signal comprising the plurality of bit sequences based on the set of filter coefficients may comprise: preparing the uplink signal comprising the plurality of bit sequences for transmission by convolving a signal obtained based on the configuration for performing uplink transmissions with an emulated channel signal obtained based on the set of filter coefficients.

[0226] The filter coefficients may be obtained based on information indicating at least one of: a type of fading experienced by, or expected to be experienced by, an uplink transmission channel, a doppler shift of the uplink transmission channel, or a power delay profile of the uplink transmission channel.

[0227] The set of filter coefficients may be configured to emulate at least one of: a propagation channel response, or at least one radio frequency imperfection resulting from an expected user handling of the user device.

[0228] The apparatus may further, subsequent to said transmitting the uplink signal comprising the plurality of bit sequences, obtain, from a network access apparatus, an indication of a selected modulation and coding scheme for performing uplink transmissions across a channel between the user device and the network access apparatus, and transmit uplink across the channel based on the selected modulation and coding scheme.

[0229] Figure 9 illustrates a method that may be performed by an apparatus for (e.g., comprised in) a network access apparatus. The network access apparatus may be as described in Figure 2. The network access apparatus may be a network access node (e.g., a gNB, base station, or similar).

[0230] During 901, the apparatus provides an indication that triggers uplink link adaptation calibration to be performed. The indication may be provided to a user device, such as the user device of Figure 8, and / or Figure 6.

[0231] The indication may be an explicit indication. For example, the indication may be expressed as a predetermined bit value in a designated field, where the absence of the designated field and / or a different bit value in the designated field from the predetermined bit value indicates that uplink link adaptation calibration is not being performed or will not be performed by the network access apparatus.

[0232] Stated differently, the indication that triggers uplink link adaptation calibration to be performed comprises a predetermined bit having a first value, wherein the absence of the predetermined bit and / or the predetermined bit having a second value indicates that performance of uplink link adaptation calibration is not being triggered to be performed.

[0233] During 902, the apparatus transmits a block of N downlink channel state information reference signals for uplink link adaptation calibration based on the indication. These may be obtained (e.g., received) by a user device during 802. The block of N downlink CSI reference signals may be configured contiguously.

[0234] It is understood that the N downlink CSI reference signals may be substituted by any N downlink signals, including N downlink reference signals. The N downlink signals may comprise a preconfigured form and / or bit sequences.

[0235] The apparatus may receive an indication of at least one channel quality metric corresponding to the block of N downlink channel state information reference signals.

[0236] The transmitting the block of N downlink channel state information reference signals may comprise transmitting different downlink channel state information reference signals comprised in said block using a plurality of different transmission powers.

[0237] The apparatus may transmit a configuration for performing uplink transmissions, and receive an uplink signal comprising a plurality of bit sequences based on the configuration (e.g., receive from the user device), wherein the configuration for performing uplink transmissions comprises: an indication of a mapping for a plurality of uplink transmission powers and a plurality of modulation and coding schemes, wherein an uplink transmission power of the plurality of uplink transmission power pairs with at least one modulation and coding scheme of the plurality of modulation and coding schemes; and / or an indication of one or more bit sequences corresponding to the plurality of bit sequences.

[0238] The apparatus may determine the configuration for performing uplink transmissions based on the received indication of at least one channel quality metric corresponding to the block of N downlink channel state information reference signals.

[0239] The apparatus may modify a preconfigured mapping of signal-to-interference-and- noise ratio to modulation and coding scheme based on a determined at least one channel qualitymetric corresponding to the received uplink signal to form a modified mapping of signal-to- interference-and-noise ratio to modulation and coding scheme.

[0240] The apparatus may select a modulation and coding scheme to be used for signalling across a channel between the user device and the network access apparatus based on a signal- to-interference-and-noise ratio of the channel and the modified mapping of signal-to- interference-and-noise ratio to modulation and coding scheme, and cause the selected modulation and coding scheme to be used for signalling across said channel.

[0241] The apparatus may provide, to the user device, an indication of a set of filter coefficients for distorting the uplink signal prior to transmission.

[0242] The filter coefficients may correspond to at least one of: a type of fading experienced by or expected to be experienced by an uplink transmission channel, a doppler shift of the uplink transmission channel, or a power delay profile of the uplink transmission channel.

[0243] The set of filter coefficients may be selected by the apparatus with an aim of emulating at least one of: a propagation channel response, or at least one radio frequency imperfection resulting from an expected user handling of the user device.

[0244] It should be understood that the apparatuses may comprise or be coupled to other units or modules etc., such as radio parts or radio heads, used in or for transmission and / or reception. Although the apparatuses have been described as one entity, different modules and memory may be implemented in one or more physical or logical entities.

[0245] It is noted that whilst some embodiments have been described in relation to 5G networks, similar principles can be applied in relation to other networks and communication systems (e.g., to 6G networks and beyond). Therefore, although certain embodiments were described above by way of example with reference to certain example architectures for wireless networks, technologies and standards, embodiments may be applied to any other suitable forms of communication systems than those illustrated and described herein.

[0246] It is also noted herein that while the above describes example embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

[0247] As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0248] In general, the various embodiments may be implemented in hardware or special purpose circuitry, software, logic or any combination thereof. Some aspects of the disclosuremay be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the disclosure is not limited thereto. While various aspects of the disclosure may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0249] As used herein, the term “circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and (b) combinations of hardware circuits and software, such as (as applicable): (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.”

[0250] This definition of circuitry applies to all uses of this term herein, including in any claims. As a further example, as used herein, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0251] The embodiments of this disclosure may be implemented by computer software executable by a data processor of the mobile device, such as in the processor entity, or by hardware, or by a combination of software and hardware. Computer software or program, also called program product, including software routines, applets and / or macros, may be stored in any apparatus-readable data storage medium and they comprise program instructions to perform particular tasks. A computer program product may comprise one or more computer- executable components which, when the program is run, are configured to carry outembodiments. The one or more computer-executable components may be at least one software code or portions of it.

[0252] Further in this regard it should be noted that any blocks of the logic flow as in the Figures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD. The physical media is a non-transitory media.

[0253] The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal ) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

[0254] The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may comprise one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), FPGA, gate level circuits and processors based on multi core processor architecture, as non-limiting examples.

[0255] Various example embodiments of the disclosure may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

[0256] The scope of protection sought for various example embodiments of the disclosure is set out by the independent claims. The example embodiments and features thereof, if any, described in this disclosure that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various example embodiments of the disclosure.

[0257] The foregoing description has provided, by way of non-limiting and illustrative examples, a full and informative description of the various example embodiments of this disclosure. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the claims. However, all such and similar modifications ofthe teachings will still fall within the various example embodiments of the disclosure as set forth in the claims. By way of non-limiting and illustrative example, there is a further example embodiment comprising a combination of one or more example embodiments with any of the other example embodiments previously discussed.

Claims

Claims 1) A method comprising: receiving, by a user device, an indication that triggers uplink link adaptation calibration to be performed; and obtaining, by the user device, a block of N downlink channel state information reference signals for uplink link adaptation calibration based on the indication. 2) The method according to claim 1, the method further comprising: determining, for each of the N downlink channel state information reference signals, a corresponding channel quality metric; and / or providing, to a network access apparatus, an indication of the determined channel quality metrics. 3) The method according to any preceding claim, further comprising: obtaining, by the user device, a configuration for performing uplink transmissions; and transmitting, by the user device, an uplink signal comprising a plurality of bit sequences based on the configuration, wherein the configuration for performing uplink transmissions comprises: an indication of a mapping for a plurality of uplink transmission powers and a plurality of modulation and coding schemes, wherein an uplink transmission power of the plurality of uplink transmission power pairs with at least one modulation and coding scheme of the plurality of modulation and coding schemes; and / or an indication of one or more bit sequences corresponding to the plurality of bit sequences. 4) The method according to claim 3, wherein the transmitting, by the user device, the uplink signal comprising the plurality of bit sequences based on the configuration further comprises: obtaining a set of filter coefficients for distorting the uplink signal prior to transmission; and transmitting the uplink signal comprising the plurality of bit sequences based on the set of filter coefficients.5) The method according to claim 4, wherein the transmitting the uplink signal comprising the plurality of bit sequences based on the set of filter coefficients comprises: preparing the uplink signal comprising the plurality of bit sequences for transmission by convolving a signal obtained based on the configuration for performing uplink transmissions with an emulated channel signal obtained based on the set of filter coefficients. 6) The method according to any of claims 4 to 5, wherein the filter coefficients are obtained based on information indicating at least one of: a type of fading experienced by, or expected to be experienced by, an uplink transmission channel, a doppler shift of the uplink transmission channel, or a power delay profile of the uplink transmission channel. 7) The method according to any of claims 4 to 6, wherein the set of filter coefficients are configured to emulate at least one of: a propagation channel response, or at least one radio frequency imperfection resulting from an expected user handling of the user device. 8) The method according to any of claims 3 to 7, the method further comprising, subsequent to said transmitting the uplink signal comprising the plurality of bit sequences: obtaining, by the user device from a network access apparatus, an indication of a selected modulation and coding scheme for performing uplink transmissions across a channel between the user device and the network access apparatus; and transmitting uplink across the channel based on the selected modulation and coding scheme. 9) The method according to any preceding claim, wherein the indication that triggers uplink link adaptation calibration to be performed comprises a predetermined bit having a first value, wherein the absence of the predetermined bit and / or the predetermined bit having a second value indicates that performance of uplink link adaptation calibration is not being triggered to be performed.10) A method comprising: providing, by a network access apparatus, an indication that triggers uplink link adaptation calibration to be performed; and transmitting, by the network access apparatus, a block of N downlink channel state information reference signals for uplink link adaptation calibration based on the indication. 11) The method according to claim 10, the method further comprising: receiving, by the network access apparatus, an indication of at least one channel quality metric corresponding to the block of N downlink channel state information reference signals. 12) The method according to any of claims 10 to 11, wherein the transmitting the block of N downlink channel state information reference signals comprises transmitting different downlink channel state information reference signals comprised in said block using a plurality of different transmission powers. 13) The method according to any of claims 10 to 12, the method further comprising: transmitting, by the network access apparatus, a configuration for performing uplink transmissions; and receiving, by the network access apparatus, an uplink signal comprising a plurality of bit sequences based on the configuration, wherein the configuration for performing uplink transmissions comprises: an indication of a mapping for a plurality of uplink transmission powers and a plurality of modulation and coding schemes, wherein an uplink transmission power of the plurality of uplink transmission power pairs with at least one modulation and coding scheme of the plurality of modulation and coding schemes; and / or an indication of one or more bit sequences corresponding to the plurality of bit sequences. 14) The method according to claim 13 when based on any of claims 11 to 12, further comprising determining the configuration for performing uplink transmissionsbased on the received indication of at least one channel quality metric corresponding to the block of N downlink channel state information reference signals. 15) The method according to any of claims 13 to 14, the method further comprising: modifying a preconfigured mapping of signal-to-interference-and-noise ratio to modulation and coding scheme based on a determined at least one channel quality metric corresponding to the received uplink signal to form a modified mapping of signal-to-interference-and-noise ratio to modulation and coding scheme. 16) The method according to claim 15, the method further comprising: selecting a modulation and coding scheme to be used for signalling across a channel between the user device and the network access apparatus based on a signal-to-interference-and-noise ratio of the channel and the modified mapping of signal-to-interference-and-noise ratio to modulation and coding scheme; and causing the selected modulation and coding scheme to be used for signalling across said channel. 17) The method according to any of claims 10 to 16, wherein the method further comprises: providing, to the user device, an indication of a set of filter coefficients for distorting the uplink signal prior to transmission. 18) The method according to claim 17, wherein the filter coefficients correspond to at least one of: a type of fading experienced by or expected to be experienced by an uplink transmission channel, a doppler shift of the uplink transmission channel, or a power delay profile of the uplink transmission channel. 19) The method according to any of claims 17 to 18, wherein the set of filter coefficients are selected by the apparatus with an aim of emulating at least one of: a propagation channel response, or at least one radio frequency imperfection resulting from an expected user handling of the user device.20) An apparatus comprising means for performing the method according to at least one of claims 1 to 9, or for performing the method according to at least one of claims 10 to 19. 21) A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method according to at least one of claims 1 to 9, or to carry out the method according to at least one of claims 10 to 19. 22) An apparatus comprising at least one processing core and at least one memory storing instructions that, when executed by the at least one processing core, cause the apparatus at least to: receive an indication that triggers uplink link adaptation calibration to be performed; and obtain a block of N downlink channel state information reference signals for uplink link adaptation calibration based on the indication. 23) An apparatus comprising at least one processing core and at least one memory storing instructions that, when executed by the at least one processing core, cause the apparatus at least to: provide an indication that triggers uplink link adaptation calibration to be performed; and transmit a block of N downlink channel state information reference signals for uplink link adaptation calibration based on the indication.

Images