Methods, apparatus and computer programs

Abstract

A method of determining actions when a band for a candidate uplink reference signal transmission is not available comprises: providing capability information to a network node about how user equipment

Description

TECHNICAL FIELD Various example embodiments relate generally to methods, apparatus, system and computer programs and in particular, but not exclusively, methods, apparatus, system and computer programs relating to uplink transmit switching. BACKGROUND 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. 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 provided by 3GPP and future standards such as 6G and beyond. BRIEF DESCRIPTION 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 thereof. Other features, aspects, and elements will be readily apparent to a person skilled in the art in view of this disclosure. According a first aspect, there is provided a user equipment comprising: means for providing capability information to a network node about a capability of the user equipment to support uplink transmit switching; means for receiving from the network node, configuration information relating to the uplink transmit switching by the user equipment for a plurality of different bands; and means for determining if a band for a candidate uplink reference signal transmission configured by an uplink reference signal configuration is available for the uplink transmit switching configured by the configuration information relating to the uplink transmit switching and determining one or more actions when the band for the candidate uplink reference signal transmission is not available. Other optional features of the first aspect may be seen from the dependent claims. According to a second aspect, there is provided a method comprising: providing capability information to a network node about a capability of the user equipment to support uplink transmit switching; receiving from the network node, configuration information relating to the uplink transmit switching by the user equipment for a plurality of different bands; and determining if a band for a candidate uplink reference signal transmission configured by an uplink reference signal configuration is available for the uplink transmit switching configured by the configuration information relating to the uplink transmit switching and determining one or more actions when the band for the candidate uplink reference signal transmission is not available. The one or more actions may comprise omitting the transmission of the respective the candidate uplink reference signal. The one or more actions may comprise re-scheduling the candidate uplink reference signal transmission to when an associated band of the plurality of different bands is active. The one or more actions may comprise re-scheduling the candidate uplink reference signal transmission to when the associated band of the plurality of different bands is active only if the candidate uplink reference signal transmission can be rescheduled within a time window. When the candidate uplink reference signal transmission is re-sched-uled, an order of transmission of one or more subsequent uplink reference signals may be maintained with respect to the candidate uplink reference signal. When the candidate uplink reference signal transmission is re-sched-uled, an order of transmission of one or more subsequent uplink reference signals may not be maintained with respect to the candidate uplink reference signal where a subsequent uplink reference signal is due to be transmitted prior to the re-sched-uled candidate uplink reference signal. The one or more actions may comprise causing a switching to the band for the candidate uplink reference signal transmission configured by the uplink reference signal configuration. The uplink reference signals may comprise sounding reference signals. The configuration information relating to the uplink transmit switching may comprise one or more patterns for the uplink transmit switching. The configuration information comprise information about one or more of: a recurring pattern for the transmitting of the uplink reference signals on the plurality of different bands; a periodicity associated with a recurring pattern for the transmitting of the uplink reference signals on the plurality of different bands; a number of times a recurring pattern for the transmitting of the uplink reference signals is to be repeated; or a pattern for the transmitting of the uplink reference signals on the plurality of different bands and an associated offset. The configuration information may comprise information about one or more of: resource configuration; resource type; a transmission comb; a sequence identity for the uplink reference signals; or spatial relation information. The method may be performed by an apparatus. The apparatus may be a user equipment. The apparatus may comprise at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to provide one or more of the methods of the second aspect. According to a third aspect, there is provided an apparatus comprising: means for receiving capability information from a user equipment about a capability of the user equipment to support uplink transmit switching; means for providing to the user equipment, configuration information relating to the uplink transmit switching by the user equipment for a plurality of different bands; and means for determining that an updated configuration for the uplink transmit switching is required when the user equipment is unable to transmit one or more uplink reference signals on one or more uplink reference signal occasions configured by the configuration information relating to uplink transmit switching. The means for determining may determine that an updated configuration for uplink transmit switching is required when the user equipment drops more than a threshold number of occurrences of the transmission of the uplink reference signals. The means for determining may determine that an updated configuration for uplink transmit switching is required when the user equipment is unable to transmit the uplink reference signal on a band at a target occurrence frequency. The uplink reference signals may comprise sounding reference signals. The configuration information relating to the uplink transmit switching may comprise one or more patterns for the uplink transmit switching. The configuration information may comprise information about one or more of: a recurring pattern for the transmitting of the uplink reference signals on the plurality of different bands; a periodicity associated with a recurring pattern for the transmitting of the uplink reference signals on the plurality of different bands; a number of times a recurring pattern for the transmitting of the uplink reference signals is to be repeated; or a pattern for the transmitting of the uplink reference signals on the plurality of different bands and an associated offset. The configuration information may comprise information about one or more of: resource configuration; resource type; a transmission comb; a sequence identity for the uplink reference signals; or spatial relation information. The apparatus may be an access node. The access node may be a base station. The access node may be a gNB. According to a fourth aspect, there is provided a method comprising: receiving capability information from a user equipment about a capability of the user equipment to support uplink transmit switching; providing to the user equipment, configuration information relating to the uplink transmit switching by the user equipment for a plurality of different bands; and determining that an updated configuration for the uplink transmit switching is required when the user equipment is unable to transmit one or more uplink reference signals on one or more uplink reference signal occasions configured by the configuration information relating to the uplink transmit switching. The method may comprise determining that an updated configuration for the uplink transmit switching is required when the user equipment drops more than a threshold number of occurrences of the transmission of the uplink reference signals. The method may comprise determining that an updated configuration for the uplink transmit switching is required when the user equipment is unable to transmit the uplink reference signal on a band at a target occurrence frequency. The uplink reference signals may comprise sounding reference signals. The configuration information relating to the uplink transmit switching may comprise one or more patterns for the uplink transmit switching. The configuration information may comprise information about one or more of: a recurring pattern for the transmitting of the uplink reference signals on the plurality of different bands; a periodicity associated with a recurring pattern for the transmitting of the uplink reference signals on the plurality of different bands; a number of times a recurring pattern for the transmitting of the uplink reference signals is to be repeated; or a pattern for the transmitting of the uplink reference signals on the plurality of different bands and an associated offset. The configuration information may comprise information about one or more of: resource configuration; resource type; a transmission comb; a sequence identity for the uplink reference signals; or spatial relation information. The method may be performed by an apparatus. The apparatus may be an access node. The access node may be a base station. The access node may be a gNB. The apparatus may comprise at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to provide one or more of the methods of the fourth aspect. According to another aspect, there is provided a computer readable medium comprising program instructions stored thereon for performing at least one of the above methods. According to an aspect, there is provided a non-transitory computer readable medium comprising program instructions stored thereon for performing at least one of the above methods. According to an aspect, there is provided a non-volatile tangible memory medium comprising program instructions stored thereon for performing at least one of the above methods. In the above, many different aspects have been described. It should be appreciated that further aspects may be provided by the combination of any two or more of the aspects described above. Various other aspects are also described in the following detailed description and in the attached claims. LIST OF THE DRAWINGS In the following, the invention will be described in greater detail with reference to the embodiments and the accompanying drawings, in which Fig. 1 shows an example of a communication network to which examples disclosed herein may be applied; Figs. 2 shows a first example of a transmission switching pattern with three examples of SRS (sounding reference signal patterns; Fig. 3 shows a first procedure of some embodiments; Fig. 4 shows a second procedure of some embodiments; Fig. 5 shows an example of an apparatus; Fig. 6 shows a first method of some embodiments; Fig. 7 shows a second method of some embodiments; Fig. 8 shows a third method of some embodiments; and Fig. 9 shows a fourth method of some embodiments. DESCRIPTION OF EMBODIMENTS The following embodiments are exemplary. Although the specification may refer to “an”, "one", or “some" embodiment's] in several locations of the text, this does not necessarily mean that each reference is made to the same embodi-ment(s), or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. Further, when a particular feature, structure, or characteristic is described in connection of an embodiment, it is within the knowledge of one skilled in the art to apply such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. It shall be understood that although the terms “first," "second” and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For the purposes of the present disclosure, the phrases "at least one of A or B”, “at least one of A and B”, and "A and / or B” means (A), (B), or (A and B). For the purposes of the present disclosure, the phrase “A, B, and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C). Embodiments described may be implemented in a communication network, such as any of the following radio access technologies (RATs): Worldwide Interoperability for Micro-wave Access (WiMAX), Global System for Mobile communications (GSM, 2G), GSM EDGE radio access Network (GERAN), General Packet Radio Service (GRPS), Universal Mobile Telecommunication System (UMTS, 3G) based on basic wideband-code division multiple access (W-CDMA), high-speed packet access (HSPA), Long Term Evolution (LTE), LTE-Advanced, and enhanced LTE (eLTE), 5G (also called NR), or any future RAT such as 6G. Moreover, communication within the communication network 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), and / or Discrete Fourier Transform spread OFDM (DFT-s-OFDM). As used herein, the term “network device" or "network node” refers to a node in a communication network via which user equipment may access the network and / or which is capable of controlling radio communication and managing radio resources within a cell. The network node or network device may be referred to as a base station (BS), an access point (AP) or an access node. The network device may be, depending on the applied technology, 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 head (RH), a remote radio head (RRH), a relay, an Integrated Access and Backhaul (1AB) node, a low power node, 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, or an aircraft network device. Moreover, in connection of split radio access network (RAN), the network device may refer to a centralised unit (CU) of a base station and / or a distributed unit (DU) of a base station. An interface between CU and DU may be referred to as an Fl interface in NR. In the split RAN architecture, node operations may be carried out, at least partly, in the central / centralized unit, CU, (e.g. server, host or node) operationally coupled to the DU, (e.g. a radio head / node). One CU may control one or more DUs, acting at least as transmit / receive (Tx / Rx) nodes. In some embodiments, the DUs may comprise e.g. a radio link control (RLC), medium access control (MAC) layer and a physical (PHY) layer, whereas the CU may comprise the layers above RLC layer, such as a packet data convergence protocol (PDCP) layer, a radio resource control (RRC) and an internet protocol (IP) layers. Other functional splits are possible too. In practice, any processing task may be performed in either the CU or the DU and the boundary where the responsibility is shifted between the CU and the DU may depend on the applied implementation. The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example, a terminal device may be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), or a Mobile Station (MS). The terminal device may include 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, USB dongles, an Internet of Things (loT) 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. A term “resource”, as used herein, may refer to radio resources in time domain, in frequency domain, in space domain, and / or in code domain. Some examples of resources include e.g. a physical resource block (PRE), a radio frame, a subframe, a time slot, a sub band, a frequency region, a sub-carrier, a beam, etc. The term "transmission” and / or "reception” may refer to wirelessly transmitting and / or receiving via a wireless propagation channel on radio resources. Fig. 1 illustrates an example of a communication network to which examples disclosed herein may be applied. The communication network or a cellular communication network may comprise a network node 110 providing one or more cells, such as cell 100, and a network node 112 providing one or more other cells, such as cell 102. Each cell may be, e.g., a macro cell, a micro cell, femto, or a pico cell, for example. The cell may define a coverage area or a service area of the corresponding access node. The network node 110 may provide a user equipment (UE) 120 (one or more UEs) with wireless access to the communication network. The wireless access may comprise downlink (DL) communication from the network node to the UE 120 and uplink (UL) communication from the UE 120 to the network node. Examples of uplink channels comprise physical uplink control channel (PUCCH) for transmitting control information and physical uplink shared channel (PUSCH) for transmitting data towards the network. Examples of downlink channels comprise physical downlink control channel (PDCCH) for transmitting control information and physical downlink shared channel (PDSCH) for transmitting data towards the user equipment. There may be a plurality of UEs 120, 122 in the system. Each of them may be served by the same or by different network nodes 110, 112. UE may be configured with dual connectivity (DC), wherein the UE, e.g. UE 120, may be connected to multiple network nodes 110, 112. The UEs 120, 122 may communicate with each other, in case device-to-device (D2D) communication interface is established between them via a so-called sidelink (SL). Such D2D communications may be referred to as machine-to-machine, peer-to-peer (P2P) communications, or ve-hicle-to-vehicle (V2V), for example. In the case of multiple network nodes in the communication network, the network nodes may be connected to each other via an interface. LTE specifications call such an interface as X2 interface. An interface between an LTE node and a 5G node, or between two 5G nodes may be called Xn interface. The network nodes 110 and 112 may be further connected via another interface to a core network 116 of the communication network. Some embodiments relate to uplink transmit switching. Uplink transmit (UL TX) switching is where a UE changes from transmitting on one band to transmitting on another band. A carrier used for communication exists on a band. The band may be a frequency band having one or more carriers. The band may be wider than a carrier. There may be more than one carrier on a band. If the carriers are adjacent to each other in frequency, the UE may be able to transmit on the two carriers with a single transmitter. In some cases, the UE may not be able to use one transmitter to transmit on two carriers on one band, and the switching may take place between two different carriers on the same frequency band. In the following discussions, reference is made to various examples where the UE switches between different bands. It should be appreciated that those examples may be modified to provide examples where the UE is switching between two carriers on the same frequency band. UL TX switching may allow a single TX chain or transmitter between to be shared in an FDD (frequency division duplex) band and a TDD (time division duplex) band. With a FDD band, a UE uses one frequency for UL and a different frequency for downlink (DL). With TDD, a UE uses one frequency for both UL and DL. The UE may be able to support MIMO (multiple input multiple output) rank 2 in the TDD band. A UE may support a switched UL mode where the UE cannot transmit simultaneously on two carriers or bands. A UE may support dual uplink mode where the UE can transmit simultaneously on two carriers or bands. The UE report a capability as to which one or other or both of the modes are supported, for both via a "both capability”. For one or more of the modes there is one or more further options depending on whether the respective transmitter chain is shared or not between the two modes. A UE may indicate a need for uplink switching. This may be, for example, in the case where the UE is configured with carrier aggregation with more than 2 uplink carriers. By way of example only, the UE may be configured with 3 or 4 UL carriers. It has been proposed that the UE switch according to DCI (downlink control information) scheduling indications. The UE may then be expected to transmit in uplink when it is scheduled or configured to be scheduled, hence switching can occur due to one or more of: PUSCH, A-SRS (aperiodic sounding reference signal) , P-SRS (periodic SRS (RRC), CG (configured grant) (type-1 and type-2 (RRC)) and PUCCH for all UCI (uplink control information) types (SR (scheduling request), HARQ-ACK (hybrid automatic repeat request acknowledgment / negative acknowledgement and CS1 (channel state information) feedback). A delay is introduced t_switch to ensure that the UE is not expected to have PUSCH ready before t_switch + PUSCH preparation time. A similar issue may arise for SRS. The gNB may need to ensure that no conflicts occur between the configured bands that requires uplink transmit switching. The current proposals may be burdensome for the gNB to manage. For example, the gNB may need to ensure PUCCH does is not fall into an undesired cell, when allocating a PDSCH. Similar issues may alternatively or additionally arise for SRS periodicity selection or allocations. Avoiding unnecessary switching may increase spectral efficiency and / or minimizes switching gaps. A switching gap is the time required to switch from one band to another. Uplink TX switching in 5G NR is based on the principle that the UE switching occasions are defined by the scheduling on the implicated cells. This scheduling defines the UE behaviour when the UE conducts UL TX switching derived based on the scheduling information. This may mean that the UE is in a situation where it may conduct uplink TX switching to follow scheduling and intended usage of the uplink physical channels and / or reference signals. The uplink channels and reference signals may comprise PUSCH, PUCCH (of all UC1 types], CG, SRS, and / or PRACH. It may be challenging to select scheduling occasions and configurations for PUSCH, PUCCH (e.g. CS1 feedback and HARQ-ACK), CG and / or SRS, that ensures that the UE can use transmit switching to switch from, for example a TDD band which has a DL symbol (and cannot be used for UL] to an FDD band supporting UL. In some embodiments, the gNB may configure the UE with a UL TX switching pattern. This may remove the need for UE-based switching decisions and constraints. In some embodiments, the gNB may derive the switching pattern. In some embodiments, The UE uses an uplink TX switching pattern which defines when the UE should be able to transmit in uplink on which bands. Each band may be one of a FDD band, TDD band, or an uplink only band, The uplink only band is sometimes referred to a supplemental uplink band. A band may comprise one carrier on the band or a plurality of carriers on the band. A carrier used for communication may be provided on a band. The band may be wider than a carrier. There may be a plurality of carriers on a band. If two carriers of a band are adjacent to each other in frequency the UE may be able to transmit on the two carriers with a single transmitter. The UE may signal capability information to the network. This capability information may indicate the ability of the UE to support uplink TX switching. The capability information may indicate the capability of the UE for uplink TX switching of at least one set of band combinations which are constrained by uplink TX switching capabilities. The capability information may provide information on one or mor constrained band combination. Such constraints may be switched UL or dual UL or simultaneous UL for two or more bands. The UE may be configured by the network with a carrier aggregation configuration. The network may provide configuration information relating to uplink transmit switching. The configuration information may comprise information about the plurality of different bands. The configuration information may comprise priority information associated with the plurality of different bands. The priority information may indicate which of the plurality of different bands is to be used in dependence on an availability of a respective one of the different bands for transmission to the network at a given time. The priority information may comprise information about a transmission priority associated with one of a respective time slot or symbol of a respective pattern for uplink transmit switching, the transmission priority indicating which of the plurality of bands has a higher priority for the respective time slot or symbol. The priority information may be provided by assigning a priority value for each respective time slot or symbol. The UE may be configured for uplink TX switching. The configuration is dependent on the configuration information. The configuration may comprise one or more of: a band combination; at least one switching pattern; handling of more than one transmitter or TX chain involved in switching; a switching gap configuration; and / or a downlink interruption pattern indication This may be associated with a CA (carrier aggregation) configuration. In some embodiments, each band in the band-combination may configured with an UL priority. This may be provided by the configuration information. The switching pattern maybe derived or determined at the UE and / or gNB using the UL priority. The determination of the switching pattern may be as follows: A highest priority band is used for UL, when it is an UL occasion on that highest priority band. If not then, the second highest priority UL band is used, when it is an UL occasion on that second highest priority band. If not, his is repeated with the next highest priority band (if there is one) and so on. If a given band is deactivated, then the UL occasions of that band may not be considered when determining the switching pattern. Where a UE has the capability for dual UL or simultaneous UL, the gNB may configure the UE to have specific switching patterns per transmit chain or transmitter. In some embodiments, when the respective switching pattern for more than one TX chain or transmitter indicates the same band at the same time, the gNB may assume that the UE may simultaneously transmit using the different transmitters on that band. In some embodiments, the UE may be configured with one transmit switching pattern. In other embodiments, the UE may be configured with two or more transmit switching patterns. In some embodiments, the access node knows when the UE is able to transmit in which band and can therefore schedule itself to receive those transmissions accordingly. The access node may be able to easily track when the UE is able to transmit on which bands. Some embodiments, relate to the providing of uplink reference signals in the case that the UE is configured with an uplink TX switching pattern. In the following examples, the uplink reference signals may be a SRS (sounding reference signal]. However, other examples of UL reference signals may be used in other embodiments. The UE may be configured by the network for uplink TX switching. The UE may receive configuration information from the network. The configuration information may comprise one or more of the following information: a band combination; priority information for the bands of the band combination; at least one switching pattern; a switching pattern for additional TX chains (if additional TX chains are available]; and a switching gap configuration The UE may be configured, by the network, with an SRS configuration. The UE may receive SRS configuration information from the network which comprises information about one or more of: a resource configuration (e.g. time and / or frequency allocation, repetition, and / or hopping pattern]; a resource type (e.g. periodic, semi-persistent, or aperiodic]; a transmission comb; a sequence identity; spatial relation information; a reoccurrence pattern; a reoccurrence pattern periodicity; an SRS uplink TX switching pattern and offset; or an SRS port specific switching pattern. The UE, when being configured with the SRS configuration and being configured with uplink TX switching pattern, may use the SRS configuration for the uplink TX switching mode. The UE may determine the SRS reoccurrence pattern based on the uplink TX switching pattern. The UE may repeat the SRS reoccurrence pattern with the granularity of the periodicity used for the uplink TX switching pattern. In this way, the periodicity may be regarded as a number of pattern periods. The UE may determine, if it is provided by the network, an SRS specific reoccurrence pattern and offset that may override the uplink TX switching pattern. An uplink switching pattern can be configured per transmitter. An SRS pattern may be configured per transmitter. The UE may expect an SRS configuration to map to an uplink TX port This may replace the need for dedicated SRS port switching as defined in 5G NR, as the gNB can configure a switching pattern per SRS port. This switching pattern may also comprise bands outside the CA configuration on which UL TX switching is configured. Reference is made to Figure 2 which shows an example of a SRS transmission pattern where an uplink TX switching pattern is provided An example of a switching pattern defined by priority bands for a three band combination with UL TX switching restrictions can be seen from Figure 2. The first band is referred to UL Band 0, the second band is referred to UL Band 1, and the third band is referred to UL Band 2. In this example, UL Band 0 is a TDD band, UL Band 1 is a TDD band, and UL Band 2 is an FDD band. UL Band 0 may be a 5ms bi-periodic pattern (e.g. DDDSU-DDSUU - where D is DL, U is UL and S is a special subframe) UL Band 1 may be a 2ms periodic pattern (e.g. DU where D is DL and U isUL). In Figure 2, "U" is used to indicate an UL time slot and” D” is used to indicate a DL time slot for UL Band 0 and UL Band 1. For UL Band 2, each time slot is an UL time slot. The fourth row indicates the switching pattern where “0” refers to UL Band 0, “1” refers to UL Band 1, and 2 refers to UL Band 2. In this example, UL Band 0 has a higher priority than UL Band 1 which in turn has a higher priority than UL Band 2. This means that an UL time slot is selected on UL Band 0, if that band has an available time slot. If there is no available UL time slot on UL Band 0, then the UL time slot on UL Band 1 is selected. If there is no available UL time slot on UL Band 1, then the UL time slot on UL Band 2 is selected. The fifth, sixth, and seventh row shows respectively first, second, and third SRS patterns defined based on the configured uplink TX switching pattern. In example 1 (SRS configuration for band 0), the UE is configured to transmit SRS at the 1st occurrence of UL in band 0. This occurs in the 9th slot in the example pattern. This has a repetition factor of 2 (which means that the SRS is transmitted twice on adjacent slots). This has a periodicity of 4 uplink TX switching patterns. This may be indicated with information as follows; Uplink TX switching pattern: 22112211001122110000 (20 slots and with 15 kHz SCS (subcarrier spacing) 20ms)- this is shown in the fourth row of Figure 2; Band for SRS: band 0; SRS reoccurrence pattern: 1st occurrence in the pattern (9th slot in this example); SRS repetition factor: 2; and SRS periodicity: 4 (i.e. 4 times 20ms hence 80ms in this example). In example 2 (SRS configuration 1) for band 1, the UE is configured to transmit SRS in the 4th and 8th occurrences of an UL slot. This occurs in the 8th and 16th slot in the example pattern. This has a repetition factor of 1 and repeats every 4 patterns. This may be indicated with information as follows; Uplink TX switching pattern: 22112211001122110000 (20 slots and with 15 kHz SCS (subcarrier spacing) 20ms)- this is shown in the fourth row of Figure 2; Band for SRS: band 1 SRS reoccurrence pattern: [4, 8] fourth and eight occurrence in the pattern (9th slot in this example); SRS repetition factor: 1; and SRS periodicity: 4 (i.e. 4 times 20ms hence 80ms in this example). In example 3 (SRS configuration 2), the UE is configured to transmit SRS in the 19th slot and is configured to do so with 2 SRS ports. This is configured with a separate uplink TX pattern for each of the SRS ports. For port 1, the pattern prioritize band 0 and for port 2, the pattern prioritizes band 1. instead of band 0 in the 19th slot. This may be indicated with information as follows; Uplink TX switching pattern: 22112211001122110000 (20 slots and with 15 kHz SCS (subcarrier spacing) 20ms)- this is shown in the fourth row of Figure 2; SRS repetition factor: 1; SRS periodicity: 4 (i.e. 4 times 20ms hence 80ms in this example); SRS reoccurrence pattern port 0: 5th occurrence of band 0 (or 19th slot) SRS reoccurrence pattern port 1: 9th occurrence (pattern as port 0, but prioritizing band 1 in slot 19); and SRS transmission comb: n2 The UE may thus be configured with a switching pattern per uplink TX transmitter. The UE may map an SRS port to an uplink TX transmitter that are assigned to two different TX chains. In another example, the gNB may configure the UE with an additional SRS switching pattern, the additional pattern may be defined by unit symbols, for example. The additional pattern may have a length 14, that would overrule the switching pattern in the indicated slots of SRS. For example, such a pattern could be used in combination with switched UL to appoint specific uplink TX switching pattern within a slot that will fit an SRS port sweep. For example a pattern for an SRS configuration , could be 0000000 0010000 starting in the 19th slot if it is only desired to allow the UE to switch to band 1 in symbol 9. An additional SRS switching pattern may be assigned to each uplink TX switching chain by associating the pattern to an SRS port. When there is no band indicated along with the SRS transmission, the UE may expect to be configured with a slot offset in the recurrence pattern, and apply the SRS transmission in the band indicated to be active by the uplink TX switching pattern. In one embodiment, instead of a relative occurrence of a particular band, a slot offset is used instead. This makes it easy to determine the timing of the SRS transmission. This may require redetermining the SRS pattern if a band is en-abled / disabled. In another embodiment, a full bitmap may be used to indicate the SRS recurrence pattern. For example for Example 3 of Figure 2, the that could be 000000000000000000010 instead of 19th slot, and for example for Example 2 of Figure 2 instead of two offsets [8, 16] the gNB can indicate 000000010000000000100. This may be useful when multiple offsets within the pattern is needed. It should be appreciated that current SRS configuration may be applied other band than when UL TX switching is active. In some embodiments, when the UE is configured with a band combination where uplink TX switching is also configured, the UE will follow the configured pattern for the UL TX switching. The UE will use a SRS configuration following a defined pattern, in some embodiments. The UE uses, in some embodiments, a dedicated SRS configuration for operation with the UL TX switching pattern. The dedicated SRS configuration may be provided to the UE by the access node. In other examples, the dedicated SRS configuration may be derived from the SRS configuration used when UL TX switching is not being used. This SRS configuration used when UL TX switching is not being used may be a so-called legacy SRS configuration and may be for example as defined in 5G specifications. Reference is made to Figure 3 which shows a first example procedure. In this example, where the UE changes the SRS configuration to a pattern based configuration when UL TX switching is configured. As referenced 1, the UE sends information about the capability of the UE. This may be referred to as capability information. The capability information may be sentto the network. For example, the capability information may be sent to an access node, for example a gNB. In the following example, reference is made to communication with a gNB. However, it should be appreciated that this is by way of example and the communication may be with any suitable access node. The described procedure of Figure 3 describes communication between one gNB and a UE. It should be appreciated that in other embodiments, the communication may be between the UE and different gNBs. The capability information may comprise information about the bands supported by the UE. The capability information may comprise information about a need for UL TX switching. As referenced 2, the access node or gNB may determine a SRS configuration. This may define when the UE is to transmit a SRS and on what band. At this time, the UE is not operating in a UL TX mode. This configuration may be a so-called legacy configuration. As referenced 3, the access node or gNB may transmit information about the determined SRS configuration to the UE. As referenced 4, the UE is configured for SRS transmission in accordance with the received information about the determined SRS configuration. As referenced 5, the UE is configured to transmit SRS in accordance with the determined SRS configuration. As referenced 6, the gNB or access node may determine that a carrier aggregation CA configuration is to be activated. When this CA configuration requires UL TX switching, the gNB will determine a UL TX switching pattern with which the UE is to be configured. The gNB may determine an updated SRS configuration or indicate how the current SRS configuration is to be modified. It should be appreciated there may be other scenarios which require UL TX switching other than CA. In those other scenarios, the gNB will determine a UL TX switching pattern with which the UE is to be configured. The gNB may determine a updated SRS configuration or indicate how the current SRS configuration is to be modified. As referenced 7, the gNB or access node provides the UE with information about the UL TX configuration. The information about the UL TX configuration may comprise information about the UL TX switching pattern which the UE is to use. The information about the UL TX configuration may comprise information about the updated SRS configuration. This may comprise the updated SRS configuration or an indication as to how the current SRS configuration is to be modified. The gNB may provide the UE with information about the CA configuration. As referenced 8, the UE may configure the UE to provide UL TX switching in accordance with the information received from the UE. The UE will configure the UE to provide SRS in accordance with the information provided by the gNB. For example, the UE may determine a SRS recurrence pattern. As referenced 9, the UE may transmit SRS in accordance with the SRS recurrence pattern while the UE is in a UL TX switching mode. In some embodiments, the UE may have at least two SRS configurations, one configuration may be used when the uplink TX switching mode is disabled and one configuration may be used when the uplink TX switching mode is enabled. In some embodiments, the UE may have more than two SRS configuration. The SRS configuration that is applied may depend for example on the plurality of bands that are being used in an active UL TX switching mode. Reference is made to Figure 4 which shows a second example procedure. In this example, where the UE is configured with more than one SRS configurations. Figure 4 does not show equivalent parts of the procedure of Figure 3 which are referenced 1 and 2. In practice, those parts of the procedure of Figure 3 may be carried out before the part of the procedure referenced 1 of Figure 4. As referenced 1, the access node or gNB may transmit information about the determined SRS configuration to the UE for a first band. This is reference band C in Figure 4. As referenced 2, the access node or gNB may the gNB or access node may determine that a carrier aggregation CA configuration is to be activated. Where this CA configuration requires UL TX switching, the gNB will determine a UL TX switching pattern with which the UE is to be configured. The gNB may determine a updated SRS configuration or indicate how the current SRS configuration is to be modified. It should be appreciated there may be other scenarios which require UL TX switching other than CA. In those other scenarios, the gNB will determine a UL TX switching pattern with which the UE is to be configured. The gNB may determine an updated SRS configuration or indicate how the current SRS configuration is to be modified. As referenced 3, the gNB or access node provides the UE with information about the UL TX configuration. The information about the UL TX configuration may comprise information about the UL TX switching pattern which the UE is to use. The information about the UL TX switching pattern may comprise information about the bands. In this example, the bands are referenced band A and band B in this example. In information about the UL TX configuration may comprise information about the updated SRS configuration. This updated SRS configuration may comprise information about the bands, bands A and B in this example. This may comprise the updated SRS configuration or an indication as to how the current SRS configuration is to be modified. The gNB may provide the UE with information about the CA configuration. The CA configuration may comprise information about the bands, bands A and B in this example. As referenced 4, if bands A and B have UL TX switching configured and the bands are to be configured for associated SRS configuration, the UE is configured to apply the SRS configuration for UL TX switching for bands A and B. As referenced 5, the UE may transmit SRS in accordance with the SRS configuration for bands A and B while the UE is in a UL TX switching mode for those bands. As referenced 6, if band C is configured, then the SRS configuration for band C (received by the UE in the part of the procedure referenced 1) is applied. As referenced 7, the UE may transmit SRS in accordance with the SRS configuration for band C. As referenced 8, the access node or gNB may determine that a band of the CA configuration is to be disbanded. In this example, band A is disable. As referenced 9, the access node or gNB may transmit information indicating that band A is being disabled. As referenced 10, if band A is disabled, then the legacy SRS configuration for band A is applied. Band A is removed from the CA configuration, hence it is not configured for UL TX switching. However, the SRS may still be applied for band A. Hence, the legacy SRS configuration for band A is applied now. As referenced 11, the UE may transmit SRS in accordance with the SRS configuration for band A. In some embodiments, the reoccurrence pattern for SRS in an UL TX switching mode may be derived from a current 5G (legacy) SRS configuration. The SRS configuration may be as in legacy 5G NR, but the UE is configured with uplink TX switching and a switching pattern. The UE will determine if the SRS configuration is compliant with the uplink switching pattern. If the SRS configuration is not compliant with the uplink switching pattern, the UE may take one or more actions. One example of an action may be that the UE drops the SRS transmission if the SRS is scheduled to be transmitted on a band that is not indicated to be active by the UL TX switching pattern. Another example of an action may be that the UE postpones an SRS transmission on a band to the nearest time occasion which matches the UL TX switching pattern. In this example, the UE may be configured with a time window. The UE may drop SRS transmissions that are postponed by a time such that the transmission would fall outside the time window. A time limit is thus provided which defines a maximum time for which the SRS transmission can be delayed. In some embodiments, where the UE postpones an SRS transmission on a band to the nearest time occasion, the order of that SRS with respect to other SRS may be maintained. This may result in one or more later SRSs being postponed. In some embodiments, there may be a limit as to a number of later SRS transmission occurrences which can be postponed. In some embodiments, where the UE postpones an SRS transmission occurrence on a band to the nearest time occasion, the order of that SRS occurrence with respect to other SRS occurrences may not be required to be maintained. In some embodiments, the gNB may configure the UE to enforce SRS UL TX switching as an action. In this example, the UE will enforce a switching that is not compliant with the UL TX switching pattern, if allowed by the gNB. This may reduce the effort required by the gNB to configure a pattern that matches the SRS transmit pattern and the UL TX switching pattern. This behaviour may be configured by a Boolean command. This command may be provided in the RRC SRS configuration. An example of such a command may be force UL Tx Switching if needed (TorceUlTxSwitchinglfNeeded). In some embodiments, the gNB may determine that an updated configuration for uplink transmit switching is required. This may be determined when the user equipment is unable to transmit one or more uplink reference signals on one or more uplink reference signal occasions configured by the configuration information relating to uplink transmit switching. In some embodiments, the gNB may determine that an updated configuration for uplink transmit switching is required when the user equipment drops more than a threshold number of occurrences of the transmission of the uplink reference signals. For example, when more than a threshold number of SRS transmissions are missed, the gNB may determine an updated configuration. In some embodiments, the gNB may determine that an updated configuration for uplink transmit switching is required when the user equipment is unable to transmit the uplink reference signal on a band at a target occurrence frequency. In some embodiments, UL TX switching may be mapped to SRS ports. In 5G NR, the UE may be configured with up to 8 SRS ports and up to 2 UL TX switching ports. In a future standards, the number of SRS ports may differ and / or the number of UL TX switching ports may differ. For example more than 2 UL TX ports may be provided. For example, 3, 4 or more UL TX ports may be provided. In some embodiments, the number of SRS ports to be used within band combinations subject to UL TX switching, may be such that the SRS ports and the number of transmitters are the same or the number of SRS ports is smaller than the number of transmitters. However, in other embodiments, number of SRS ports may be greater than the number of ports involved in UL TX switching. In this example, the gNB may configure an UL TX switching pattern for the SRS ports involved. The UE may determine which UL TX transmitter it assigns to an SRS port configuration. This UE may take into account the configuration. The UE may maintain the pairing of a SRS port and the assigned UL TX transmitter as long as the SRS configuration is active. This may mean that the UE may comply with the spatial relationship of which the SRS configuration is associated. This may be defined by the gNB or access node via RRC spatial relation information (spatialRelationlnfo). Reference is made to FIG. 6 which shows a method of some example embodiments. This method may be performed by an apparatus. The apparatus may comprise or be user equipment. The apparatus may comprise suitable means, such as circuitry for providing the method. Alternatively or additionally, the apparatus may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor cause the apparatus at least to provide the method below. Alternatively or additionally, the apparatus may be such as discussed in relation to FIG. 5. The method may be provided by computer program code or computer executable instructions. The method comprises as referenced Al, providing capability information to a network node about a capability of a user equipment to support uplink transmit switching. The method comprises as referenced A2, receiving from the network node, information relating to the uplink transmit switching by the user equipment for a plurality of different bands and configuration information for transmitting of uplink reference signals for the plurality of the different bands. The method comprises as referenced A3, transmitting the uplink reference signals on one or more transmit occurrences for the uplink reference signals based on the configuration information for transmitting of the uplink reference signals for the plurality of the different bands and the information relating to the uplink transmit switching. The method may be modified to include one or more of the previously described options. Reference is made to FIG.7 which shows a method of some example embodiments. This method may be performed by an apparatus. The apparatus may comprise or be an access node. The access node may be a base station, for example a gNB. The apparatus may comprise suitable means, such as circuitry for providing the method. Alternatively or additionally, the apparatus may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor cause the apparatus at least to provide the method below. Alternatively or additionally, the apparatus may be as discussed in relation to FIG. 5. The method may be provided by computer program code or computer executable instructions. The method comprises as referenced Bl, receiving capability information from a user equipment about a capability of the user equipment to support uplink transmit switching. The method comprises as referenced B2, providing to the user equipment, information relating to the uplink transmit switching by the user equipment for a plurality of different bands and configuration information for transmitting of uplink reference signals for the plurality of the different bands. The method comprises as referenced B3, receiving the uplink reference signals on one or more transmit occurrences for the uplink reference signals based on the configuration information for transmitting of the uplink reference signals for the plurality of the different bands and the information relating to the uplink transmit switching. The method may be modified to include one or more of the previously described options. Reference is made to FIG. 8 which shows a method of some example embodiments. This method may be performed by an apparatus. The apparatus may comprise or be a user equipment. The apparatus may comprise suitable means, such as circuitry for providing the method. Alternatively or additionally, the apparatus may comprise at least one processor and at least one memoiy storing instructions that, when executed by the at least one processor cause the apparatus at least to provide the method below. Alternatively or additionally, the apparatus may be as discussed in relation to FIG. 5. The method may be provided by computer program code or computer executable instructions. The method comprises as referenced Cl, providing capability information to a network node about a capability of a user equipment to support uplink transmit switching. The method comprises as referenced C2, receiving from the network node, configuration information relating to the uplink transmit switching by the user equipment for a plurality of different bands. The method comprises as referenced C3, determining if a band for a candidate uplink reference signal transmission configured by an uplink reference signal configuration is available for the uplink transmit switching configured by the configuration information relating to the uplink transmit switching and determining one or more actions when the band for the candidate uplink reference signal transmission is not available. The method may be modified to include one or more of the previously described options. Reference is made to FIG.9 which shows a method of some example embodiments. This method may be performed by an apparatus. The apparatus may comprise or be an access node. The access node may be a base station, for example a gNB. The apparatus may comprise suitable means, such as circuitry for providing the method. Alternatively or additionally, the apparatus may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor cause the apparatus at least to provide the method below. Alternatively or additionally, the apparatus may be as discussed in relation to FIG. 5. The method may be provided by computer program code or computer executable instructions. The method comprises as referenced DI, receiving capability information from a user equipment about a capability of the user equipment to support uplink transmit switching. The method comprises as referenced D2, providing to the user equipment, configuration information relating to the uplink transmit switching by the user equipment for a plurality of different bands. The method comprises as referenced D3, determining that an updated configuration for the uplink transmit switching is required when the user equipment is unable to transmit one or more uplink reference signals on one or more uplink reference signal occasions configured by the configuration information relating to the uplink transmit switching. The method may be modified to include one or more of the previously described options. Fig. 5 shows, by way of example, a block diagram of an apparatus 10. The apparatus 10 comprises, for example, at least one processor 12 and at least one memory 14 storing instructions 15 that, when executed by the at least one processor, cause the apparatus 10 at least to perform the method or methods as disclosed herein, and any of the embodiments thereof. In an example, the at least one memory and the instructions (e.g. a computer program code, software), are configured, with the at least one processor, to cause the apparatus 10 to perform the method or methods as disclosed herein, and any of the embodiments thereof. A processor 12 may comprise circuitry, or be constituted as circuitry or circuitries, the circuitry or circuitries being configured to perform phases of methods in accordance with example embodiments described herein. As used in this application, 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 memoiy(ies) that work together to cause an apparatus, such as a user equipment, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a mi-croprocessor(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. This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, 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. The memory 14 may be implemented using any suitable data storage technology. The memory may comprise a database for storing data. The memory 14 may be at least in part external to apparatus 10 but accessible to apparatus 10. The instructions 15 may be comprised in a computer readable medium or a non-transitory computer readable medium. A 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. random-access memory, RAM, vs. read only memory, ROM). For example, the apparatus 10 is a terminal device, such as the UE of Fig. 1. As another example, the apparatus is comprised in such a terminal device, e.g. as a chipset configured to control the terminal device. The apparatus 10 may be caused or configured to perform at least the method of any one or more of the embodiments described. As another example, the apparatus 10 is a network node, e.g. the access node or base station of Fig. 1. In another embodiment, the apparatus is comprised in such a network node, e.g. as a chipset configured to control the network node. The apparatus 10 may be caused or configured to perform at least the method of any one or more of the embodiments described. The apparatus may comprise one or more entities of any of protocol layers, such as a MAC entity, an RRC entity, an RLC entity, a PDCP entity or a PHY entity. In some embodiments, the entity is configured to perform at least the method of any one or more of the embodiments described. The apparatus 10 comprises a radio interface 16. The radio interface 16 may provide the apparatus 10 with communication capabilities. The radio interface 16 may comprise a receiver configured to receive information in accordance with at least one cellular or non-cellular standard. The radio interface 16 may comprise a transmitter configured to transmit information in accordance with at least one cellular or non-cellular standard. The receiver may comprise more than one receiver. The transmitter may comprise more than one transmitter. The radio interface 16 may comprise a transceiver configured to receive and transmit information in accordance with at least one cellular or non-cellular standard. The transceiver may comprise more than one transceiver. The apparatus 10 may optionally comprise a user interface 18 comprising, for example, at least one of a keypad, a microphone, a touch display, a display, a speaker, etc. The user interface 18 may be used to control the apparatus by the user. The user interface 18 may be external to the apparatus 10. For example, the apparatus 10 may be connected to another device, such as a computer, either via wireless or wired connection, and the apparatus 10 is controlled by the user via the computer. In an embodiment, at least some of the processes described herein may be carried out by an apparatus comprising means for carrying out at least some of the described processes. Means for performing method steps as disclosed herein may include software and / or hardware components of the apparatus 10. For example, the at least one processor 12, the memory 14, and the computer program code form means for carrying out the method or methods as disclosed herein, and any of the embodiments thereof. As used herein the term “means” is to be construed in singular form, i.e. referring to a single element, or in plural form, i.e. referring to a combination of single elements. Therefore, terminology “means for [performing A, B, C]", is to be interpreted to cover an apparatus in which there is only one means for performing A, B and C, or where there are separate means for performing A, B and C, or partially or fully overlapping means for performing A, B, C. Further, terminology “means for performing A, means for performing B, means for performing C" is to be interpreted to cover an apparatus in which there is only one means for performing A, B and C, or where there are separate means for performing A, B and C, or partially or fully overlapping means for performing A, B, C. Even though the invention has been described above with reference to an example according to the accompanying drawings, it is clear that the invention is not restricted thereto but can be modified in several ways within the scope of the appended claims. Therefore, all words and expressions should be interpreted broadly, and they are intended to illustrate, not to restrict, the embodiment. It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. Further, it is clear to a person skilled in the art that the described embodiments may, but are not required to, be combined with other embodiments in various ways.

Claims

1. A user equipment comprising:means for providing capability information to a network node about a capability of the user equipment to support uplink transmit switching;means for receiving from the network node, configuration information relating to the uplink transmit switching by the user equipment for a plurality of different bands; andmeans for determining if a band for a candidate uplink reference signal transmission configured by an uplink reference signal configuration is available for the uplink transmit switching configured by the configuration information relating to the uplink transmit switching and determining one or more actions when the band for the candidate uplink reference signal transmission is not available.

2. The user equipment as claimed in claim 1, wherein the one or more actions comprises omitting the transmission of the respective the candidate uplink reference signal.

3. The user equipment as claimed in claim 1, wherein the one or more actions comprises re-scheduling the candidate uplink reference signal transmission to when an associated band of the plurality of different bands is active.

4. The user equipment as claimed in claim 3, wherein the one or more actions comprises re-scheduling the candidate uplink reference signal transmission to when the associated band of the plurality of different bands is active only if the candidate uplink reference signal transmission can be rescheduled within a time window.

5. The user equipment as claimed in claim 3 or 4, wherein when the candidate uplink reference signal transmission is re-scheduled, an order of transmission of one or more subsequent uplink reference signals is maintainedwith respect to the candidate uplink reference signal.

6. The user equipment as claimed in claim 3 or 4, wherein when the candidate uplink reference signal transmission is re-scheduled, an order of transmission of one or more subsequent uplink reference signals is not maintained with respect to the candidate uplink reference signal where a subsequent uplink reference signal is due to be transmitted prior to the re-scheduled candidate uplink reference signal.

7. The user equipment as claimed in claim 1, wherein the one ormore actions comprise causing a switching to the band for the candidate uplink reference signal transmission configured by the uplink reference signal configuration.

8. The user equipment as claimed in any preceding claim, wherein the uplink reference signals comprise sounding reference signals.

9. The user equipment as claimed in any preceding claim, wherein the configuration information relating to the uplink transmit switching comprises one or more patterns for the uplink transmit switching.

10. The user equipment as claimed in any preceding claim, wherein the configuration information comprises information about one or more of:a recurring pattern for the transmitting of the uplink reference signals on the plurality of different bands;a periodicity associated with a recurring pattern for the transmitting of the uplink reference signals on the plurality of different bands;a number of times a recurring pattern for the transmitting of the uplink reference signals is to be repeated; ora pattern for the transmitting of the uplink reference signals on the plurality of different bands and an associated offset.

11. The user equipment as claimed in any preceding claim, wherein the configuration information comprises information about one or more of:resource configuration;resource type;a transmission comb;a sequence identity for the uplink reference signals; orspatial relation information.

12. An apparatus comprising:means for receiving capability information from a user equipment about a capability of the user equipment to support uplink transmit switching;means for providing to the user equipment, configuration information relating to the uplink transmit switching by the user equipment for a plurality of different bands; andmeans for determining that an updated configuration for the uplink transmit switching is required when the user equipment is unable to transmit one or more uplink reference signals on one or more uplink reference signal occasions configured by the configuration information relating to the uplink transmit switching.

13. The apparatus as claimed in claim 12, wherein the means for determining determines that an updated configuration for the uplink transmit switching is required when the user equipment drops more than a threshold number of occurrences of the transmission of the uplink reference signals.

14. The apparatus as claimed in claim 12, wherein the means for determining determines that an updated configuration for the uplink transmit switching is required when the user equipment is unable to transmit the uplink reference signal on a band at a target occurrence frequency.

15. A method comprising:providing capability information to a network node about a capability of a user equipment to support uplink transmit switching;receiving from the network node, configuration information relating to the uplink transmit switching by the user equipment for a plurality of different bands; anddetermining if a band for a candidate uplink reference signal transmission configured by an uplink reference signal configuration is available for the uplink transmit switching configured by the configuration information relating to the uplink transmit switching and determining one or more actions when the band for the candidate uplink reference signal transmission is not available.

16. The method as claimed in claim 15, wherein the one or more actions comprises omitting the transmission of the respective the candidate uplink reference signal.

17. The method as claimed in claim 15, wherein the one or more actions comprises re-scheduling the candidate uplink reference signal transmission to when an associated band of the plurality of different bands is active.

18. The method as claimed in claim 17, wherein the one or more actions comprises re-scheduling the candidate uplink reference signal transmission to when the associated band of the plurality of different bands is active only if the candidate uplink reference signal transmission can be rescheduled within a time window.

19. The method as claimed in claim 17 or 18, wherein when the candidate uplink reference signal transmission is re-scheduled, an order of transmission of one or more subsequent uplink reference signals is maintained with respect to the candidate uplink reference signal.

20. The method as claimed in claim 17 or 18, wherein when the candidate uplink reference signal transmission is rescheduled, an order of transmission of one or more subsequent uplink reference signals is not maintained with respect to the candidate uplink reference signal where a subsequent uplink reference signal is due to be transmitted prior to the re-scheduled candidate uplink reference signal.

21. The method as claimed in claim 15, wherein the one or more actions comprising causing a switching to the band for the candidate uplink reference signal transmission configured by the uplink reference signal configuration.

22. The method as claimed in any of claims 15 to 21, wherein the configuration information comprises one or more patterns for the uplink transmit switching.

23. The method as claimed in any of claims 15 to 22, wherein the uplink reference signals comprise sounding reference signals.

24. A method comprising:receiving capability information from a user equipment about a capability of the user equipment to support uplink transmit switching;providing to the user equipment, configuration information relating to the uplink transmit switching by the user equipment for a plurality of different bands; anddetermining that an updated configuration for the uplink transmit switching is required when the user equipment is unable to transmit one or more uplink reference signals on one or more uplink reference signal occasions configured by the configuration information relating to the uplink transmit switching.

25. A computer program comprising computer executable instructions which when executed by at least one processor provide the method of any one of claims 12 to 24.

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