Apparatus, method and computer program

Abstract

An indication of a bandwidth expansion to be applied to a positioning signal, e.g. a positioning reference signal or a sounding reference signal, received at the apparatus, e.g. user equipment or base station, from a transmitter, e.g. base station or user equipment, is obtained 701, e.g. received from a network entity, and the positioning signal is received 702, wherein the positioning signal comprises a plurality of symbols in n sub-carriers. An expanded positioning signal is generated 703 based on the received positioning signal and the indication of the bandwidth expansion to be applied, and a time of arrival of the positioning signal is determined 704 based on the expanded positioning signal. The arrival time of the symbols may be frequency independent and the bandwidth expansion to be applied may be associated with a positioning signal received from a given transmitter. Generating the expanded positioning signal may comprise adding L sub-carriers to the n sub-carriers of the received positioning signal.

Description

Field The present application relates to a method, apparatus, system and computer program and in particular but not exclusively to resource saving in positioning bandwidth aggregation. Background A communication system can be seen as a facility that enables communication sessions between two or more communication devices, or provides communication devices access to a 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. 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 4G (4th Generation), 5G (5th Generation) standards provided by 3GPP. Summary In a first aspect there is provided an apparatus comprising means for performing obtaining an indication of a bandwidth expansion to be applied to a positioning signal received at the apparatus from a transmitter, receiving the positioning signal, wherein the positioning signal comprises a plurality of symbols in n sub-carriers, generating an expanded positioning signal based on the received positioning signal and the indication of the bandwidth expansion to be applied and determining a time of arrival of the positioning signal based on the expanded positioning signal. The arrival time of the symbols may be substantially frequency independent. Obtaining the indication of the expansion to be applied may comprise receiving the indication from a network entity. The apparatus may comprise means for performing receiving a request for receiver processing capability from the network entity and providing an indication of receiver processing capability to the network in response. The bandwidth expansion to be applied may be associated with a positioning signal received from a given transmitter. Generating the expanded positioning signal may comprise adding L sub-carriers to the n subcarriers of the received positioning signal. The L sub-carriers may comprise generated symbols. A pattern of the symbols of the n subcarriers may be repeated in the generated symbols of the L sub-carriers. At least one of the L sub-carriers may be null. The indication of the expansion to be applied may comprise an indication of at least one of the following: expansion direction, a frequency gap between the L sub-carriers and the received n sub-carriers, an asymmetric offset, a number of sets of generated symbols comprised in the L sub-carriers or a deviation of a generated symbol pattern in the L sub-carriers from a given symbol pattern. The apparatus may comprise a user equipment. The transmitter may comprise a base station and the positioning signal may comprise a positioning reference signal. The apparatus may comprise a base station. The transmitter may comprise a user equipment and the positioning signal may comprise a sounding reference signal. In a second aspect there is provided an apparatus comprising means for performing determining a bandwidth of a positioning signal provided by a transmitter of the positioning signal, the positioning signal comprising a plurality of symbols in n sub-carriers, determining, based on a metric, a bandwidth expansion of the positioning signal to be applied at the receiver of the positioning signal, providing an indication of the bandwidth to the transmitter; and providing an indication of the bandwidth expansion to be applied to the receiver. The arrival time of the symbols at the receiver may be substantially frequency independent. The apparatus may comprise means for performing providing a request for receiver processing capability to the receiver and receiving an indication of receiver processing capability, wherein determining the expansion of the positioning signal is further based on the receiver processing capability. The bandwidth expansion to be applied may be associated with a positioning signal received from the transmitter. Expansion of the positioning signal may comprise adding L sub-carriers to the received n subcarriers of the received positioning signal. The indication of the expansion to be applied may comprise an indication of at least one of the following: expansion direction, a frequency gap between the L sub-carriers and the received sub-carriers, an asymmetric offset, a number of sets of generated symbols comprised in the L sub-carriers or a deviation of a generated symbol pattern in the L sub-carriers from a given symbol pattern. The metric may comprise at least one of an accuracy metric or a resource saving metric. The receiver may comprise a user equipment, the transmitter may comprise a base station and the positioning signal may comprise a positioning reference signal. The receiver may comprise a base station, the transmitter may comprise a user equipment and the positioning signal may comprise a sounding reference signal. In a third aspect there is provided a method comprising obtaining an indication of a bandwidth expansion to be applied to a positioning signal received at the apparatus from a transmitter, receiving the positioning signal, wherein the positioning signal comprises a plurality of symbols in n sub-carriers, generating an expanded positioning signal based on the received positioning signal and the indication of the bandwidth expansion to be applied and determining a time of arrival of the positioning signal based on the expanded positioning signal. The arrival time of the symbols may be substantially frequency independent. Obtaining the indication of the expansion to be applied may comprise receiving the indication from a network entity. The method may comprise receiving a request for receiver processing capability from the network entity and providing an indication of receiver processing capability to the network in response. The bandwidth expansion to be applied may be associated with a positioning signal received from a given transmitter. Generating the expanded positioning signal may comprise adding L sub-carriers to the n subcarriers of the received positioning signal. The L sub-carriers may comprise generated symbols. A pattern of the symbols of the n subcarriers may be repeated in the generated symbols of the L sub-carriers. At least one of the L sub-carriers may be null. The indication of the expansion to be applied may comprise an indication of at least one of the following: expansion direction, a frequency gap between the L sub-carriers and the received n sub-carriers, an asymmetric offset, a number of sets of generated symbols comprised in the L sub-carriers or a deviation of a generated symbol pattern in the L sub-carriers from a given symbol pattern. The method may be performed at a user equipment. The transmitter may comprise a base station and the positioning signal may comprise a positioning reference signal. The method may be performed at a base station. The transmitter may comprise a user equipment and the positioning signal may comprise a sounding reference signal. In a fourth aspect there is provided a method comprising determining a bandwidth of a positioning signal provided by a transmitter of the positioning signal, the positioning signal comprising a plurality of symbols in n sub-carriers, determining, based on a metric, a bandwidth expansion of the positioning signal to be applied at the receiver of the positioning signal, providing an indication of the bandwidth to the transmitter; and providing an indication of the bandwidth expansion to be applied to the receiver. The arrival time of the symbols at the receiver may be substantially frequency independent. The method may comprise providing a request for receiver processing capability to the receiver and receiving an indication of receiver processing capability, wherein determining the expansion of the positioning signal is further based on the receiver processing capability. The bandwidth expansion to be applied may be associated with a positioning signal received from the transmitter. Expansion of the positioning signal may comprise adding L sub-carriers to the received n subcarriers of the received positioning signal. The indication of the expansion to be applied may comprise an indication of at least one of the following: expansion direction, a frequency gap between the L sub-carriers and the received sub-carriers, an asymmetric offset, a number of sets of generated symbols comprised in the L sub-carriers or a deviation of a generated symbol pattern in the L sub-carriers from a given symbol pattern. The metric may comprise at least one of an accuracy metric or a resource saving metric. The receiver may comprise a user equipment, the transmitter may comprise a base station and the positioning signal may comprise a positioning reference signal. The receiver may comprise a base station, the transmitter may comprise a user equipment and the positioning signal may comprise a sounding reference signal. In a fifth aspect there is provided an apparatus comprising at least one processor, and at least one memory storing instructions which, when executed by the processor, cause the apparatus at least to perform the method according to the third or fourth aspect. In a sixth aspect there is provided a computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the method according to the third or fourth aspect. In a seventh aspect there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method according to the third or fourth aspects. 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 Embodiments will now be described, by way of example only, with reference to the accompanying Figures in which: Figure 1 shows a schematic diagram of an example 5GS communication system; Figure 2 shows a schematic diagram of an example mobile communication device; Figure 3 shows a schematic diagram of an example control apparatus; Figure 4 shows a schematic diagram of a time-domain based positioning scheme; Figure 5 shows an illustrative example of time domain pulse widths of a signal as signal bandwidth increases; Figure 6 shows a plot of achievable accuracy as measured by standard deviation against bandwidth; Figure 7 shows a flowchart of a method according to an example embodiment; Figure 8 shows a flowchart of a method according to an example embodiment; Figure 9 shows a block diagram of a method according to an example embodiment; Figure 10 shows a block diagram of an expanded signal according to an example embodiment; Figure 11 shows a signalling flow diagram according to an example embodiment; Figure 12 shows a block diagram of an expanded signal according to an example embodiment; Figure 13 shows a signalling flow diagram according to an example embodiment; Figure 14 shows a signalling flow diagram according to an example embodiment; Figure 15 shows a signalling flow diagram according to an example embodiment; Figure 16 shows a signalling flow diagram according to an example embodiment. Detailed description Before explaining in detail the examples, certain general principles of a wireless communication system and mobile communication devices are briefly explained with reference to Figure 1, Figure 2 and Figure 3 to assist in understanding the technology underlying the described examples. An example of a suitable communications system is the 5G or NR concept. Network architecture in NR may be similar to that of LTE-advanced. Base stations of NR systems may be known as next generation NodeBs (gNBs). Changes to the network architecture may depend on the need to support various radio technologies and finer Quality of Service (QoS) support, and some on-demand requirements for e.g. QoS levels to support Quality of Experience (QoE) for a user. Also network aware services and applications, and service and application aware networks may bring changes to the architecture. Those are related to Information Centric Network (ICN) and User-Centric Content Delivery Network (UC-CDN) approaches. NR may use Multiple Input - Multiple Output (MIMO) antennas, many more base stations or nodes than the LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and perhaps also employing a variety of radio technologies for better coverage and enhanced data rates. Future networks may utilise network functions virtualization (NFV) which is a network architecture concept that proposes virtualizing network node functions into “building blocks” or entities that may be operationally connected or linked together to provide services. A virtualized network function (VNF) may comprise one or more virtual machines running computer program codes using standard or general type servers instead of customized hardware. Deployments may be cloud-native network function (CNF) based, where network functions comprise one or more pods. Cloud computing or data storage may also be utilized. In radio communications this may mean node operations are to be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head. It is also possible that node operations will be distributed among a plurality of servers, nodes or hosts. It should also be understood that the distribution of labour between core network operations and base station operations may differ from that of LTE or may even be non-existent. Figure 1 shows a schematic representation of a 5G system (5GS) 100. The 5GS may comprise a user equipment (UE) 102 (which may also be referred to as a communication device or a terminal), a 5G radio access network (5GRAN) 104, a 5G core network (5GCN) 106, one or more internal or external application functions (AF) 108 and one or more data networks (DN) 110. An example 5G core network (CN) comprises functional entities. The 5GCN 106 may comprise one or more Access and mobility Management Functions (AMF) 112, one or more session management functions (SMF) 114, an authentication server function (AUSF) 116, a Unified Data Management (UDM) 118, one or more user plane functions (UPF) 120, a Unified Data Repository (UDR) 122 and / or a Network Exposure Function (NEF) 124. The UPF is controlled by the SMF (Session Management Function) that receives policies from a PCF (Policy Control Function). The 5GCN may comprise a Location Management Function (LMF) 126. The LMF is responsible for receiving measurements and assistance information from a mobile device or NG-RAN and computing the position of a UE. The CN may be connected to a UE via the Radio Access Network (RAN) or through fixed access via a non-3GPP Interworking Function (N3IWF). The 5GRAN may comprise one or more gNodeB (gNB) Distributed Unit (DU) functions connected to one or more gNodeB (gNB) Centralized Unit (CU) functions. The RAN may comprise one or more access nodes. A User Plane Function (UPF) referred to as PDU Session Anchor (PSA) may be responsible for forwarding frames back and forth between the DN and the tunnels established over the 5G towards the UE(s) exchanging traffic with the DN. A possible mobile communication device will now be described in more detail with reference to Figure 2 showing a schematic, partially sectioned view of a communication device 200. Such a communication device is often referred to as user equipment (UE) or terminal. An appropriate mobile communication device may be provided by any device capable of sending and receiving radio signals. Non-limiting examples comprise a mobile station (MS) or mobile device such as a mobile phone or what is known as a ’smart phone’, a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), personal data assistant (PDA) or a tablet provided with wireless communication capabilities, voice over IP (VoIP) phones, portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehiclemounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), smart devices, wireless customerpremises equipment (CPE), an Internet of Things (loT) device, an industrial loT device, tag device or any combinations of these or the like. A mobile communication device may provide, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and so on. Users may thus be offered and provided numerous services via their communication devices. Non-limiting examples of these services comprise two-way or multi-way calls, data communication or multimedia services or simply an access to a data communications network system, such as the Internet. Users may also be provided broadcast or multicast data. Non-limiting examples of the content comprise downloads, television and radio programs, videos, advertisements, various alerts, and other information. A mobile device is typically provided with at least one data processing entity 201, at least one memory 202 and other possible components 203 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The data processing, storage and other relevant components can be provided on an appropriate circuit board and / or in chipsets. This feature is denoted by reference 204. The user may control the operation of the mobile device by means of a suitable user interface such as key pad 205, voice commands, touch sensitive screen or pad, combinations thereof or the like. A display 208, a speaker and a microphone can be also provided. Furthermore, a mobile communication device may comprise appropriate connectors (either wired or wireless) to other devices and / or for connecting external accessories, for example hands-free equipment, thereto. The mobile device 200 may receive signals over an air or radio interface 207 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Figure 2 transceiver apparatus is designated schematically by block 206. The transceiver apparatus 206 may be provided for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device. Figure 3 shows an example of a control apparatus 300 for a communication system, for example to be coupled to and / or for controlling a station of an access system, such as a RAN node, e.g. a base station, eNB or gNB, a relay node or a core network node such as an MME or Serving Gateway (S-GW) or Packet Data Network Gateway (P-GW), or a core network function such as AMF / SMF, or a server or host. The method may be implemented in a single control apparatus or across more than one control apparatus. The control apparatus may be integrated with or external to a node or module of a core network or RAN. In some embodiments, base stations comprise a separate control apparatus unit or module. In other embodiments, the control apparatus can be another network element such as a radio network controller or a spectrum controller. In some embodiments, each base station may have such a control apparatus as well as a control apparatus being provided in a radio network controller. The control apparatus 300 can be arranged to provide control on communications in the service area of the system. The control apparatus 300 comprises at least one memory 301, at least one data processing unit 302, 303 and an input / output interface 304. Via the interface the control apparatus can be coupled to a receiver and a transmitter of the base station. The receiver and / or the transmitter may be implemented as a radio front end or a remote radio head. In a communication system, positioning is used to determine the position of a device in the communication system. The position of a moving object (car, robot, drone,...) may be crucial, or even critical, to know accurately, for example in autonomous driving use cases, industrial use cases or for general network purposes. Time-domain positioning techniques include TDoA (time-difference-of-arrival) orToA (time-of-arrival). TDoA and ToA are based on the principle of measuring the arrival time of a signal at a device and using the departure time of the signal from a transmitter to derive a time of flight. The time of flight is then used for a distance calculation which can be used to determine the position of the device with reference to the transmitter. As an example, the signal to be measured may be a positioning reference signal (PRS) in downlink (DL) or a sound reference signal (SRS) in uplink (UL). An example general open-area positioning scheme is depicted in Figure 4. The downlink direction is shown, but without loss of generality the direction of signalling could be reversed. The number of base stations shown in Figure 4 is three, although any higher number of base stations (BS) (or, more generally, TRP) may be used. Using the symbols from Figure 4, the distance calculation is made by the formula Di =c-(Tu-TOri), (Eq. 1) where i = A,B or C. The transmission time moment To i is ideally the same for all the BSs. The arrival time Tu naturally changes depending on the distance for BS A, BS B or BS C. The coordinate triples (X, Y, H) per BS (=TRP) are known, being the locations of BSs. Ri - Ri (Eq. 2) The subtraction shown in equation 2 is defined as the Time-of-Flight (ToF). The ToF is per transmitter (in the example shown in Figure 4, per BS). As Eq. 2 indicates, the time-of-flight is calculated from the system clocks; the transmitter clock (value) is subtracted from the receivers’ clocks. For an accurate distance calculation, the arrival time of the signal should be measured as accurately as possible. The time of arrival measurement accuracy depends, at least in part, on the bandwidth of the signal to be measured. The greater the bandwidth, the better the accuracy of the positioning process. As discussed below, the received reference signal content is known and so one example method used to measure the arrival time is the autocorrelation function, where the receiver generated copy of the reference signal is delayed so that the correlation gets the maximum value. The correlation peak in time-domain is the arrival time. The narrower the bandwidth, the more rounded (in the time-domain) the peak is. This means the sampling of the autocorrelation response may not find the (theoretically) correct peak value, but the measurement has the uncertainty of the width of the peak value. By Increasing the bandwidth, the autocorrelation peak value becomes narrower in the time-domain, and so the uncertainty of the measurement value decreases. The distribution of the location estimates is thus narrower, and the accuracy of the measurement of the time of arrival has improved. Figure 5 shows an Illustrative example of time domain pulse widths of a signal with a narrower bandwidth on the left and a wider bandwidth on the right. The peak of the narrower bandwidth is broader than that of the wider bandwidth. In more detail, the achievable accuracy of the time-based positioning method can be established via the standard deviation of the time of arrival, ol°A , defined as ^oA =--- (Eq. 3) where c is the speed of light, P is received power, No is noise spectral density, T is the integration / measurementtime. The parameter BW{ denotes the bandwidth of carrier frequeny fi and corresponding wavelength A;, which is used for the positioning measurements. One positioning use case is for a factory-type environments. Objects moving in the factory, e.g., devices such as robots, or anything potentially harmful if colliding with others, should know their location with a good accuracy, e.g., tens of centimeters, at least horizontally. There are multiple example techniques to reach such an accuracy, including the maximal use of available bandwidth (the environment could comprise a private network so the local operator (factory workplace management) might prioritize the positioning use case), repetitive use of reference signals, oversampling of signals in the receiving phase or maximal use of antennae used to receive the signal transmitted by the device. This may lead to high cost and high number of RRHs and antennae. Also the computational effort may be increased. Further, the bandwidth is limited, e.g., by the regulation. Thus, the physics set the upper bound for the achievable accuracy. One example use case is the factory tool troller positioning. A factory environment may be deployed with several TRPs (transmission reception points) or remote antennae only with a DU in a nearby location. The same issues may be applicable to other example positioning use cases such as openarea installations in the field, although the number of the receiving antennae may be less than in a factory type environment. In a field installation, such as that shown in Figure 4, the basic positioning procedure may require at minimum three receiving (or transmitting) antennae, but if the signal coverage is enough for more transceivers and the network loading enables to use a higher number of transceivers, the accuracy might be improved a little A positioning reference signal (PRS) definition is found in TS 38.211, section 7.4.1.7.2, and the mapping to physical resources (also known as comb pattern) in section 7.4.1.7.3. The specification defines the creation of the bit sequence rm for a symbol as: r(m) =-^(1- 2c(2m)) + / ^(1 - 2c(2m + 1)) (Eq. 4). The pseudo-random sequence c is explained in the same specification. Respectively, the uplink reference signal, i.e., sounding reference signal, is given in section 6.4.1.4. Figure 6 shows a plot of achievable accuracy (defined by o^oA) with parameter value = 8.57cm,P / No = 15dB. Hz} against the increasing bandwidth of a signal (in this example, SRS). It can be seen from Figure 6, that the achievable accuracy of the ToA in sensitive to the configured bandwidth of the reference signal. Equation 3 is one possible example of defining accuracy, and the expressions may change for different system configurations, i.e., OFDM, etc. However, the underlying relationship between the parameters, e.g., o7oA oc 1 / BW, holds with different scalings, and thus Figure 6 provides an overview and trend of achievable accuracy with the reference signal bandwidth. The bandwidth of a signal is, however, limited by the available spectrum in an operator network, which is the hard limit for any bandwidth aggregation technique. The bandwidth is limited also from the resourcing point of view; how much the operator can afford to allocate its limited resources to positioning purposes, this may be considered a soft limit for bandwidth aggregation. That is, the bandwidth cannot be increased without compromising other factors, and in practice the operator must compromise between customer requests and available resources. Limited BW for the positioning signal limits the accuracy of UE positioning in the time-domain methods. The accuracy of the positioning improves proportional to the BW increase. 3GPP standardization work in the work item Expanded and Improved NR Positioning [RP-232670] included the bandwidth aggregation. Based on the study, PRS / SRS bandwidth aggregation for intra-band contiguous carriers is concluded as feasible for single chain Tx / Rx architectures at both the UE and gNB. Figure 7 shows a flowchart of a method according to an example embodiment. In 701, the method comprises obtaining an indication of a bandwidth expansion to be applied to a positioning signal received at the apparatus from a transmitter. In 702, the method comprises receiving the positioning signal, wherein the positioning signal comprises a plurality of symbols in n sub-carriers. In 703, the method comprises generating an expanded positioning signal based on the received positioning signal and the indication of the bandwidth expansion to be applied. In 704, the method comprises determining a time of arrival of the positioning signal based on the expanded positioning signal. The method may comprise providing the determined time of arrival of the positioning signal to a network entity. The network entity may comprise the transmitter or a network function, e.g., a LMF. Obtaining the indication of the expansion to be applied may comprise receiving the indication from a network entity, e.g., a network function such as a LMF. The method may be performed at a user equipment. In this case the transmitter may comprise a base station and the positioning signal may comprise a PRS. The method may be performed at a base station, TRP or remote antenna (or the DU of such a remote antenna). In this case the transmitter may comprise a user equipment and the positioning signal may comprise a SRS. Figure 8 shows a flowchart of a method according to an example embodiment. In 801, the method comprises determining a bandwidth of a positioning signal provided by a transmitter of the positioning signal, the positioning signal comprising a plurality of symbols in n sub-carriers. In 802, the method comprises determining, based on a metric, a bandwidth expansion of the positioning signal to be applied at the receiver of the positioning signal. In 803, the method comprises providing an indication of the bandwidth to the transmitter. In 804, the method comprises providing an indication of the bandwidth expansion to be applied to the receiver. The method may be performed at a network entity, for example a network function, such as, but not limited to a LMF. The receiver may comprise a user equipment, the transmitter may comprise a base station and the positioning signal may comprise a PRS. Alternatively, or in addition, the receiver may comprise a base station, the transmitter may comprise a user equipment and the positioning signal comprises SRS. The method as described with reference to Figure 8 may comprise providing a request for receiver processing capability (e.g., BB BW capacity) to the receiver and receiving an indication of receiver BB processing capability. Determining the expansion of the positioning signal may be further based on the receiver BB processing capability. The metric may comprise at least one of an accuracy metric, e.g., an accuracy target, or a resource saving metric The methods described with reference to Figures 7 and 8 may provide a technique, which may be referred to as positioning signal (e.g., PRS or SRS) expansion. The positioning signal expansion may provide a low-cost solution to increase the bandwidth using standardized and / or established positioning techniques. The method may apply to any time-domain based positioning techniques. The method may be release independent. The problem that it solves is the positioning accuracy; the wider the bandwidth the higher the accuracy. It is assumed that The Time-of-Flight (ToF) of positioning signal (whether PRS or SRS) symbols in a positioning use case is frequency independent, i.e., that the arrival time of the symbols of the positioning signal is substantially frequency independent. Thus, it is assumed that all the symbols of a positioning signal received from a transmitter have one and the same ToF. This assumption is derived from a concept which is referred to herein as velocity flatness (VF). The assumption of VF can be reasoned as follows. Theoretically, the over-the-air channel is frequency dependent, but more often the frequency dependency of the channel is about the signal fading, while in the present case the fading of different frequency components (symbols) is not an issue as long as the sensitivity of the receiver is good enough to capture the fading symbol. To alter the ToF, the electromagnetic parameters sr and / or pr of the media in the over-the-air channel should be frequency dependent over the bandwidth used. er and / or pr define the velocity of the electromagnetic propagation through the formula v= -^=, where c = speed of light in the vacuum. For air as a medium, the velocity remains constant with high accuracy. The error due to the VF assumption is negligible. As a result of the assumption all the symbols of the positioning signal (whether PRS or SRS) received from a transmitter are assumed to arrive at the same time at the receiver. A LMF may be the controller of the expansion process performed by the receiver. In an example embodiment, LMF controls the involvement of BSs, which may be, as in the example of Figure 4, at minimum three BSs (or antennae, if remote antennae are used) in a normal application in the field. LMF may have different set of requirements per BS. The reason for varying the requirements may lie in the channel conditions; one of the directions may have more complex propagation environment, or the distance may be significantly different compared to the distances from other BSs to the target device to be positioned (UE). The bandwidth expansion to be applied may be associated with a positioning signal received from the transmitter. Required accuracy may depend on the use case. The LMF knows its uncertainty per positioning method and per used resources. Thus, if the use case requires to use the expansion method, the LMF is aware of parameters. In one example use case, the operator defines the allocation to be used for the positioning, per loading over the time. Thus, the allocation may change depending on the network loading. The operator releases resources from the positioning to other use cases by applying the expansion method described here. The physical frequencies, or the spectrum, per operator is limited by the regulation, thus the spectrum is the asset set the operator has in use, and if an operation could be served with less resources but keeping the quality the same or even better, it is an improvement to the operator. Therefore, it may be desire to balance the positioning accuracy for different positioning use cases and the resources available. In the end, the work is done by LMF. Thus, LMF may define a smaller amount of physical resources to be used are available(e.g., the metric may be a resource saving metric). This may be per BS. Figure 9 shows a block diagram of signal arrival and ToA estimation in a receiver. The dashed line includes the proposed technique (positioning signal expansion in the frequency domain) to improve the estimate of ToA. Physical resources may be saved by transmitting less bandwidth while ToA estimation accuracy is improved because the bandwidth can be increased by the positioning signal expansion, as described below, for example, with reference to Figures 10 and 12. A standard measurement procedure may be performed using the increased bandwidth. This leads to improved time-of-arrival accuracy. Generating the expanded positioning signal may comprises adding L sub-carriers to the n subcarriers of the received positioning signal. The L sub-carriers may comprise generated symbols. A pattern of the symbols of the n sub-carriers may be repeated in the generated symbols of the L sub-carriers. Alternatively, or in addition, at least one of the L sub-carriers are null. The positioning signals used are known by the receiver. The receiver can add on top of a received signal, extra symbols (bandwidth expansion) because it knows the symbol pattern and the symbols’ contents. Adding extra symbols does not violate any symbol pattern creation. While the base station controls the parameters used to generate the pseudo-random sequence, it means the base station knows the sequence transmitted. Thus, no extra signalling between the base station(s) and the UE is needed when the base station(s) is (are) receiving and applying the addition of generated symbols on top of the received symbols. Similarly, when the UE is receiving the base station signals by definition the used parameters (more precisely, it is LMF to control the positioning occasion to every involved base station) are known to the UE, and no extra signalling is needed. The addition of generated symbols to the received symbol pattern increases the bandwidth of the signal. Figure 10 shows an example of an expanded positioning signal. Sub-carriers n to n+11 are the physically received n sub-carriers and sub-carriers n+12 to n+23 are the additional L sub-carriers. The symbols in sub-carriers n to n+11 (as shown by the dotted shading) are the physically received symbols, the symbols in n+12 to n+23 (as shown by the dashed shading) are the generated symbols added in the receiver. For simplicity, only a small section of the addition is shown in this example, and only the single-sided option is used. Figure 11 shows a signalling diagram of an example embodiment In the steps below RS is the abbreviation for Reference Signal and per BS means that the physical signal between every BS and UE is defined separately, depending on the specific conditions in the field. At minimum three BSs (or TRPs) may be used. The condition is that they are applied (transmitting or receiving, depending on the positioning scheme) at the same time. The DL direction is shown (e.g., PRS from BS to UE) in the signalling diagram, but without loss of generality the diagrams could be reversed (i.e. SRS from UE to BS). In step 1, there is initialization of the positioning process by LMF in which all involved BSs are activated. In step 2, the LMF indicates to the BSs and UEs to transmit / receive and process PRS signals. The LMF may take into account an operator’s positioning use case guidelines and / or the current network loading before indicating to BSs and UEs in step 2. In step 3, the LMF deduces VF, i.e. that the positioning signal expansion can be used. In step 4, the LMF requests the UE to report its BB BW capacity to ensure positioning signal expansion is feasible. This is an example of providing a request for receiver processing capability (e.g., BB BW capacity) to the receiver and receiving an indication of receiver processing capability. In step 5, based on the positioning use case, the LMF defines how much physical spectrum (BW) is used per BS, including which comb pattern of PRS symbols is used and based on the accuracy target and the UE indicated BB BW, the LMF defines how much is the applied RS expansion per BS. The accuracy target is an example of a metric on which a bandwidth expansion may be based, wherein the metric is an accuracy metric. In this example embodiment, the bandwidth expansion of the positioning signal to be applied at the receiver of the positioning signal is determined based on the metric and the receiver processing capability. In step 6, the LMF indicates the BW of the PRS signal per BS to each BS and indicates the positioning signal expansion to the UE. In step 7, each BS transmits PRS at the same time and a standard positioning process is applied to receive the comb pattern of (M) PRS -symbols in (N) resource elements (REs). The N REs are an example of the received n sub-carriers. Theoretically, the transmissions of BSs could happen at different times this may not be practical because of clocks and other real field issues and would require a static condition, i.e., no movement is allowed within the measurement window. In step 8, generated symbols, following the time-domain pattern of the received symbols, are added on L REs or sub-carriers on top of the received N REs in frequency-domain to generated an expanded positioning signal. In step 9, autocorrelation is performed with the expanded positioning signal and the ToA per BS is calculated using the expanded positioning signal. The ToA is reported to the LMF In step 10, the position of the UE is calculated at the LMF based on the ToAs determined at the UE based on the expanded positioning signal. The indication of the expansion to be applied may comprise an indication of at least one of the following: expansion direction, a frequency gap between the L sub-carriers and the received n sub-carriers, an asymmetric offset, a number of sets of generated symbols comprised in the L sub-carriers or a deviation of a generated symbol pattern in the L subcarriers from a given symbol pattern. The indication of the expansion to be applied may be associated with a given transmitter. Where the indication of the expansion comprises an indication of expansion direction, the generated symbols may be added to L sub-carriers in decreasing the subcarrier indexes, see the symbols in sub-carriers n-1 to n-5 in Figure 12 (as shown by the hashed shading). Equally, both top and bottom placements exist simultaneously. Therefore, the additional symbols can be located anywhere in the frequency domain referred to the received band. Every BS is controlled separately by LMF, e.g., for reasons of interferences. In an uncontrolled case the expansion might extend over the bandwidth of other cells or other operators, which should be counted when defining the expansion direction (and the amount of added symbols). Figure 13 shows a signalling flow according to an example embodiment. The signalling flow includes the steps of Figure 11 but also includes the LMF sending an indication of the expansion direction. The generated symbols may be also a distance from the received one, i.e., there may be a frequency gap between the received n sub-carriers and the generated set of symbols in the L sub-carriers. The generated symbols may be placed unsymmetrically (e.g., have an asymmetric offset) if both top and bottom placements are used. Any number of sets of symbols is supported, if there is any constraint from any system component to split the expansion in parts. Figure 14 shows a signalling flow according to an example embodiment. The signalling flow includes the steps of Figure 11 but also includes the LMF sending an indication of the expansion continuity e.g., an indication of a frequency gap between the L sub-carriers and the received n sub-carriers, an asymmetric offset and / or, a number of sets of generated symbols comprised in the L sub-carriers. Since the generated symbols are known by the receiver, there is no obligation to use the standard (TS 38.211) defined symbol bit sequences for the expanded parts. It should be understood that this deviation from the standard pattern does not conflict with compliance to the network because this pattern invariance is UE internal operation. For the autocorrelation, or any other method used to measure the delay, in a pattern invariant case the receiver knows to use a non-standard copy of the received and expanded signal. In such a case the received symbols can be copied, with their symbol internal r(m) sequence as such. In other words, the symbol r(l) could be a copy of r(m), even though I * m. Figure 15 shows a signalling flow according to an example embodiment. The signalling flow includes the steps of Figure 11 but also includes the LMF sending an indication of the expansion pattern invariance, e.g., deviation of a generated symbol pattern in the L subcarriers from a given symbol pattern. The time domain pattern for the extended part(s) can be any pattern, not necessarily a standard defined pattern (comb pattern). The standard format is the most cost-efficient, but sometimes there may be a reason to use another pattern format, for example the IFFT applied could be optimised with another pattern. The symbol content in a non-standard pattern may defined by the system, where the system is either LMF, BS or UE. That is the indication of the expansion may comprise a deviation of a generated symbol pattern in the L sub-carriers from a given symbol pattern. Figure 16 shows a signalling flow according to an example embodiment. The signalling flow includes the steps of Figure 11 but also includes the LMF sending an indication of the expansion non-standard pattern. Methods may allow to set the generated symbols to any resource elements within the available operator’s band. The contiguous spectrum may provide the best accuracy. However, it is noted that the technique is applicable also to any non-contiguous case with carrier aggregation or other BW aggregation techniques (e.g., techniques like SUL or NR-U). Furthermore, RedCap UE with limited RF and BB bandwidths makes greatly use of this technique (with or without the frequency hopping). The method may be provided to a network with any size of band. An operator’s lower or upper limit of the band is not limiting the applied total bandwidth. Thus, also the narrow bandwidth FDD bands are well-suited to time-domain positioning technologies with the presented supplement When considering the PRS comb patterns from multiple base stations (or from TRPs in the general case), the proposed PRS expansion is fine also in such a scenario, because while the UE receives the defined pattern at minimum from three base stations, which means the patterns have to be aligned appropriately in the time and frequency domains to avoid overlapping patterns, the LMF takes care of the pattern definition and synchronization of the base stations. Expanding the patterns’ regularity maintains the non-overlapping scenario, and there is no interference issue presented because of the expansion technique. Methods described here are backward compatible with previous releases as well as applicable to future 6G releases. The VF assumption means that the difference in ToA between the case that the system had sent the full bandwidth in physical signal and the case where positioning signal expansion is applied, is negligible. The increase in BW size may increase positioning accuracy while allowing for resource (spectrum) or battery saving. The bandwidth of the measured signal may be increased without requiring HW changes either to the transmitter nor to the receiver. Therefore, the methods are cost-effective Indeed, the method may be considered to be transparent for the transmitter. Therefore, the upgrade of the technique even to the existing base stations is feasible. Similarly, from the UE point of view, no new requirements are set to the UE capability. Thus, the operator’s issues said above are both overcome. In the case of a high number of UEs, where UE could be any type of device to be positioned, which are sending SRS symbols, interference of the symbols might occur. For example, there may be energy leakage between the symbols, e.g., if their coding (same symbol, same frequency) is too close to each other. In such a case the proposed technique helps to reduce the interference because we can separate more devices in the frequency domain by limiting their physical transmitted bands to smaller splits and not overlapping anymore. loT devices usually have the requirementof battery time which, for example, be upto 10 years. The positioning of loT devices is very sensitive to the positioning energy consumption, because GPS (or generally, GNSS) is power hungry. Whenever possible, it is beneficial to replace or complement the GNSS positioning by network-based positioning as provided herein. When the accuracy requirement for an loT device is not high, the bandwidth and thus the energy consumption can be reduced significantly. An apparatus may comprise means for obtaining an indication of a bandwidth expansion to be applied to a positioning signal received at the apparatus from a transmitter, receiving the positioning signal, wherein the positioning signal comprises a plurality of symbols in n subcarriers, generating an expanded positioning signal based on the received positioning signal and the indication of the bandwidth expansion to be applied and determining a time of arrival of the positioning signal based on the expanded positioning signal. The apparatus may comprise a receiver, such as a user equipment as described with reference to Figure 2 or base station (or a control apparatus for a base station as described with reference to Figure 3), be the receiver or be comprised in the receiver or a chipset for performing at least some actions of / for the receiver. An apparatus may comprise means for determining a bandwidth of a positioning signal provided by a transmitter of the positioning signal, the positioning signal comprising a plurality of symbols in n sub-carriers, determining, based on a metric, a bandwidth expansion of the positioning signal to be applied at the receiver of the positioning signal, providing an indication of the bandwidth to the transmitter and providing an indication of the bandwidth expansion to be applied to the receiver. The apparatus may comprise a network function such as, but not limited to a function for location management, e.g., LMF, be the, network function or be comprised in the network function or a chipset for performing at least some actions of / for the network function. In an embodiment, the apparatus comprising a network function refers to a device / apparatus which is configured to perform or performs at least part of functionalities of the network function or to a device / apparatus which comprises circuitry (e.g., chipset) configured to perform or performing at least part of functionalities of the network function. 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. 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 such as 6G networks or 5G-Advanced networks. 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. 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. 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. In general, the various embodiments may be implemented in hardware or special purpose circuitry, software, logic or any combination thereof. Some aspects of the disclosure may 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. 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 memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and hardware circuit(s) and or processor(s), such as a microprocessor(s) ora 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 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 computerexecutable components which, when the program is run, are configured to carry out embodiments. The one or more computer-executable components may be at least one software code or portions of it. 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. 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). 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. 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. The scope of protection sought for various embodiments of the disclosure is set out by the independent claims. The embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the disclosure. The foregoing description has provided byway of non-limiting examples a full and informative description of the exemplary embodiment 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 appended claims. However, all such and similar modifications of the teachings of this disclosure will still fall within the scope of this invention as defined in the appended claims. Indeed, there is a further embodiment comprising a combination of one or more embodiments with any of the other embodiments previously discussed.

Claims

1. An apparatus comprising means for performing: obtaining an indication of a bandwidth expansion to be applied to a positioning signal received at the apparatus from a transmitter;receiving the positioning signal, wherein the positioning signal comprises a plurality of symbols in n sub-carriers;generating an expanded positioning signal based on the received positioning signal and the indication of the bandwidth expansion to be applied; anddetermining a time of arrival of the positioning signal based on the expanded positioning signal.

2. The apparatus according to claim 1, wherein the arrival time of the symbols is substantially frequency independent.

3. The apparatus according to claim 1 or claim 2, wherein obtaining the indication of the expansion to be applied comprises receiving the indication from a network entity.

4. The apparatus according to claim 3 comprising means for performing: receiving a request for receiver processing capability from the network entity; and providing an indication of receiver processing capability to the network in response.

5. The apparatus according to any of claims 1 to 4, wherein the bandwidth expansion to be applied is associated with a positioning signal received from a given transmitter.

6. The apparatus according to claims 1 to 5, wherein generating the expanded positioning signal comprises adding L sub-carriers to the n sub-carriers of the received positioning signal.

7. The apparatus according to claim 6, wherein the L sub-carriers comprise generated symbols and a pattern of the symbols of the n sub-carriers is repeated in the generated symbols of the L sub-carriers.

8. The apparatus according to claim 6 or claim 7, wherein at least one of the L subcarriers are null.

9. The apparatus according to any of claims 6 to 8, wherein the indication of the expansion to be applied comprises an indication of at least one of the following: expansion direction, a frequency gap between the L sub-carriers and the received n sub-carriers, an asymmetric offset, a number of sets of generated symbols comprised in the L sub-carriers or a deviation of a generated symbol pattern in the L sub-carriers from a given symbol pattern.

10. The apparatus according to any of claims 1 to 9, comprising a user equipment, wherein the transmitter comprises a base station and the positioning signal comprises a positioning reference signal.

11. The apparatus according to any of claims 1 to 9, comprising a base station, wherein the transmitter comprises a user equipment and the positioning signal comprises a sounding reference signal.

12. An apparatus comprising means for performing: determining a bandwidth of a positioning signal provided by a transmitter of the positioning signal, the positioning signal comprising a plurality of symbols in n subcarriers;determining, based on a metric, a bandwidth expansion of the positioning signal to be applied at the receiver of the positioning signal;providing an indication of the bandwidth to the transmitter; andproviding an indication of the bandwidth expansion to be applied to the receiver.

13. The apparatus according to claim 12, wherein the arrival time of the symbols at the receiver is substantially frequency independent.

14. The apparatus according to claim 12 or claim 13, comprising means for performing: providing a request for receiver processing capability to the receiver; and receiving an indication of receiver processing capability, wherein determining the expansion of the positioning signal is further based on the receiver processing capability.

15. The apparatus according to any of claims 12 to 14, wherein the bandwidth expansion to be applied is associated with a positioning signal received from the transmitter.

16. The apparatus according to claims 12 to 15, wherein expansion of the positioning signal comprises adding L sub-carriers to the received n sub-carriers of the received positioning signal.

17. The apparatus according to claim 16, wherein the indication of the expansion to be applied comprises an indication of at least one of the following: expansion direction, a frequency gap between the L sub-carriers and the received sub-carriers, an asymmetric offset, a number of sets of generated symbols comprised in the L subcarriers or a deviation of a generated symbol pattern in the L sub-carriers from a given symbol pattern.

18. The apparatus according to any of claims 12 to 17, wherein the metric comprises at least one of an accuracy metric or a resource saving metric.

19. The apparatus according to any of claims 12 to 18, wherein the receiver comprises a user equipment, wherein the transmitter comprises a base station and the positioning signal comprises a positioning reference signal.

20. The apparatus according to any of claims 12 to 18, wherein the receiver comprises a base station, wherein the transmitter comprises a user equipment and the positioning signal comprises a sounding reference signal.

21. A method comprising:obtaining an indication of a bandwidth expansion to be applied to a positioning signal received at the apparatus from a transmitter;receiving the positioning signal, wherein the positioning signal comprises a plurality of symbols in n sub-carriers;generating an expanded positioning signal based on the received positioning signal and the indication of the bandwidth expansion to be applied; anddetermining a time of arrival of the positioning signal based on the expanded positioning signal.

22. A method comprising:determining a bandwidth of a positioning signal provided by a transmitter of the positioning signal, the positioning signal comprising a plurality of symbols in n subcarriers;determining, based on a metric, a bandwidth expansion of the positioning signal to be applied at the receiver of the positioning signal;providing an indication of the bandwidth to the transmitter; and providing an indication of the bandwidth expansion to be applied to the receiver.

23. A computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: obtaining an indication of a bandwidth expansion to be applied to a positioning signal received at the apparatus from a transmitter;receiving the positioning signal, wherein the positioning signal comprises a plurality of symbols in n sub-carriers;generating an expanded positioning signal based on the received positioning signal and the indication of the bandwidth expansion to be applied; and determining a time of arrival of the positioning signal based on the expanded positioning signal.

24. A computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: determining a bandwidth of a positioning signal provided by a transmitter of the positioning signal, the positioning signal comprising a plurality of symbols in n subcarriers;determining, based on a metric, a bandwidth expansion of the positioning signal to be applied at the receiver of the positioning signal;providing an indication of the bandwidth to the transmitter; andproviding an indication of the bandwidth expansion to be applied to the receiver.

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