WO2023153965A1

WO2023153965A1 - Network-controlled user equipment sampling frequency

Info

Publication number: WO2023153965A1
Application number: PCT/SE2022/050157
Authority: WO
Inventors: Pål FRENGER; Erik Larsson
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2022-02-14
Filing date: 2022-02-14
Publication date: 2023-08-17
Anticipated expiration: 2024-08-14

Abstract

There is provided mechanisms for network-controlled UE sampling frequency. A first UE is assigned a first set of time-space-frequency (TSF) resources. The first UE is instructed to under-sample signals received by the first UE and defined by the first set of TSF resources. A second UE is assigned a second set of TSF resources. Thesecond set of TSF resources are non-overlapping with the first set of TSF resources in a discrete-time spectrum when the first set of TSF resources is under-sampled. The signals defined by the first set of TSF resources and signals defined by the second set of TSF resources are simultaneously transmitted.

Description

NETWORK-CONTROLLED USER EQUIPMENT SAMPLING FREQUENCY

TECHNICAL FIELD

Embodiments presented herein relate to methods, a network node, a user equipment, computer programs, and a computer program product for network-controlled user equipment sampling frequency.

JOINT RESEARCH AGREEMENT

The project leading to this application has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 101015956.

BACKGROUND

Consider a communication system with access points (APs) provided with multiple antennas. Such APs might be configured to operate at comparatively high carrier frequencies (e.g. in the Terahertz region), and in nominal frequency bands having a comparatively large bandwidth (B_o). As an illustrative example, for sixth generation (6G) telecommunication systems it is envisioned that this bandwidth could be in the order of 10 GHz. However, these are just some examples of numerical values, and the herein disclosed inventive concept is not limited to the numerical values just presented.

Assume that each AP transmits, simultaneously, data destined to (at least) two of its served user equipment (UE). The data rate per UE can sometimes be relatively low, and does not require the full nominal frequency band for transmission. This enables the different UEs to be served using frequency multiplexing.

In a typical scenario, only a small part of the frequency band maybe in use. For example, consider that B_o = 10 GHz and that a given AP is to simultaneously serve 20 active UEs, each requiring a 100 MHz bandwidth, then 80% of the spectrum would be unused. For example, consider that B_o = 200 MHz and that a given AP is to simultaneously serve four active UEs, each requiring 10 MHz, then also in this case 80% of the spectrum would be unused.

If a UE samples the entire nominal frequency band at the Nyquist frequency (i.e., at a sampling frequency, or rate of 2B₀ real-valued samples per second), the UE power consumption can become very high. Often the UE has no use for the entire nominal frequency band (which could be up to io GHz in a 6G telecommunication system), but can be satisfied with a bandwidth which is much lower (perhaps only loo MHz). In terms of UE power usage (i.e., battery life) there is thus a significant drawback for the UE in this case to maintain a high sampling rate that supports the full nominal frequency band.

Hence, there is a need for power-efficient operations of UE, particularly, but not exclusively, in communication system having a comparatively large nominal frequency band.

SUMMARY

An object of embodiments herein is to address the above issues. In particular, the above issues are addressed by providing techniques for network-controlled UE sampling frequency.

According to a first aspect there is presented a method for network-controlled UE sampling frequency. The method is performed by a network node. The method comprises assigning, to a first UE, a first set of time-space-frequency resources in a nominal frequency band with bandwidth B_o in a continuous-time spectrum. The method comprises instructing the first UE to sample signals received by the first UE and defined by the first set of time-space-frequency resources with a sampling frequency f_s, where f_s < 2B₀. The method comprises assigning, to a second UE, a second set of time-space-frequency resources in the nominal frequency band B_o. The second set of time-space-frequency resources are non-overlapping with the first set of time-space-frequency resources in a discrete-time spectrum when the first set of time-space-frequency resources is sampled with the sampling frequency f_s. The method comprises simultaneously transmitting the signals defined by the first set of time-space-frequency resources towards the first UE and signals defined by the second set of time-space-frequency resources towards the second UE.

According to a second aspect there is presented a network node for network- controlled UE sampling frequency. The network node comprises processing circuitry. The processing circuitry is configured to cause the network node to assign, to a first UE, a first set of time-space-frequency resources in a nominal frequency band with bandwidth B_o in a continuous-time spectrum. The processing circuitry is configured to cause the network node to instruct the first UE to sample signals received by the first UE and defined by the first set of time-space-frequency resources with a sampling frequency f_s, where f_s < 2B₀. The processing circuitry is configured to cause the network node to assign, to a second UE, a second set of time-space-frequency resources in the nominal frequency band B_o. The second set of time-space-frequency resources are non-overlapping with the first set of time-space-frequency resources in a discrete-time spectrum when the first set of time-space-frequency resources is sampled with the sampling frequency f_s. The processing circuitry is configured to cause the network node to simultaneously transmit the signals defined by the first set of time-space-frequency resources towards the first UE and signals defined by the second set of time-space-frequency resources towards the second UE.

According to a third aspect there is presented a network node for network-controlled UE sampling frequency. The network node comprises an assign module configured to assign, to a first UE, a first set of time-space-frequency resources in a nominal frequency band with bandwidth B_o in a continuous-time spectrum. The network node comprises an assign module configured to instruct the first UE to sample signals received by the first UE and defined by the first set of time-space-frequency resources with a sampling frequency f_s, where f_s < 2B₀. The network node comprises an assign module configured to assign, to a second UE, a second set of time-space-frequency resources in the nominal frequency band B_o. The second set of time-space-frequency resources are non-overlapping with the first set of time-space-frequency resources in a discrete-time spectrum when the first set of time-space-frequency resources is sampled with the sampling frequency f_s. The network node comprises a transmit module configured to simultaneously transmit the signals defined by the first set of time-space-frequency resources towards the first UE and signals defined by the second set of time-space-frequency resources towards the second UE.

According to a fourth aspect there is presented a computer program for network- controlled UE sampling frequency, the computer program comprising computer program code which, when run on processing circuitry of a network node, causes the network node to perform a method according to the first aspect. According to a fifth aspect there is presented a method for network-controlled UE sampling frequency. The method is performed by a UE. The method comprises receiving instructions from a network node serving the UE to sample signals defined by a first set of time-space-frequency resources with a sampling frequency f_s < 2B₀, where B_o represents a bandwidth of a nominal frequency band in a continuous-time spectrum. The method comprises receiving the signals defined by the first set of time- space-frequency resources. The method comprises sampling the received signals with the sampling frequency f_s.

According to a sixth aspect there is presented a UE for network-controlled UE sampling frequency. The UE comprises processing circuitry. The processing circuitry is configured to cause the UE to receive instructions from a network node serving the UE to sample signals defined by a first set of time-space-frequency resources with a sampling frequency f_s < 2B₀, where B_o represents a bandwidth of a nominal frequency band in a continuous-time spectrum. The processing circuitry is configured to cause the UE to receive the signals defined by the first set of time-space-frequency resources. The processing circuitry is configured to cause the UE to sample the received signals with the sampling frequency f_s.

According to a seventh aspect there is presented a UE for network-controlled UE sampling frequency. The UE comprises a receive module configured to receive instructions from a network node serving the UE to sample signals defined by a first set of time-space-frequency resources with a sampling frequency f_s < 2B₀, where B_o represents a bandwidth of a nominal frequency band in a continuous-time spectrum. The UE comprises a receive module configured to receive the signals defined by the first set of time-space-frequency resources. The UE comprises a sample module configured to sample the received signals with the sampling frequency f_s.

According to an eighth aspect there is presented a computer program for network- controlled UE sampling frequency, the computer program comprising computer program code which, when run on processing circuitry of a UE, causes the UE to perform a method according to the fifth aspect.

According to a ninth aspect there is presented a computer program product comprising a computer program according to at least one of the fourth aspect and the eighth aspect and a computer readable storage medium on which the computer program is stored. The computer readable storage medium could be a non-transitory computer readable storage medium.

Advantageously, these aspects enable significant savings in the power consumptions of electrical circuits (such as analogue-to-digital converters, digital front-end components, etc.) in the UE.

Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, module, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, module, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive concept is now described, by way of example, with reference to the accompanying drawings, in which:

Fig. i shows an example of signal spectra according to an example;

Fig. 2 is a schematic diagram illustrating a communication network according to embodiments;

Figs. 3 and 7 are flowcharts of methods according to embodiments;

Figs. 4 and 5 show examples of signal spectra according to embodiments;

Fig. 6 schematically illustrates aggregated traffic and sampling frequency as a function of time according to embodiments;

Fig. 8 is a signalling diagram according to embodiments; Fig. 9 is a schematic diagram showing functional units of a network node according to an embodiment;

Fig. io is a schematic diagram showing functional modules of a network node according to an embodiment;

Fig. n is a schematic diagram showing functional units of a UE according to an embodiment;

Fig. 12 is a schematic diagram showing functional modules of a UE according to an embodiment; and

Fig. 13 shows one example of a computer program product comprising computer readable means according to an embodiment.

DETAILED DESCRIPTION

The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the inventive concept are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description. Any step or feature illustrated by dashed lines should be regarded as optional.

As disclosed above, there is a need for power-efficient operations of UE, particularly, but not exclusively, in communication system having a comparatively large nominal frequency band.

The embodiments disclosed herein therefore relate to mechanisms for network- controlled UE sampling frequency. In order to obtain such mechanisms there is provided a network node, a method performed by the network node, a computer program product comprising code, for example in the form of a computer program, that when run on processing circuitry of the network node, causes the network node to perform the method. In order to obtain such mechanisms there is further provided a UE, a method performed by the UE, and a computer program product comprising code, for example in the form of a computer program, that when run on processing circuitry of the UE, causes the UE to perform the method.

As an introductory example, it is noted that depending on the spectrum of the continuous-time signal, the minimum sampling rate to avoid aliasing can in some cases be significantly below the Nyquist frequency. Reference is made to the illustrative numerical example of Fig. i. Fig. 1(a) shows the doble-sided continuoustime signal spectrum 710 of a signal. Hence the Nyquist frequency is 900 Hz. Sampling with f_s = 900 Hz is thus sufficient for perfect signal reconstruction, and results in the double-sided discrete-time signal spectrum 720 in Fig. 1(b) where only the part of the signal spectrum from -1/ 2 to 1/2 is relevant, from which the original signal can be easily recovered. But in this very example, sampling with a third of the Nyquist frequency, i.e., f_s = 300 Hz, is sufficient. Sampling with 300 Hz yields the discrete-time signal with the double-sided discrete-time signal spectrum 730 in Fig. 1(c) from which the original signal can also be recovered. Hence, no information is lost in the sampling even though the sampling frequency is significantly less than the Nyquist frequency. Aliasing occurs, but does not result in distortion in this case. Hence, there could be scenarios where the UE can use a sampling frequency that is significantly lower than the Nyquist frequency to still recover the original signal, thus enabling the UE power consumption to be lowered.

However, due to inference caused by transmissions from other access points or even signals transmitted from the serving access point towards other UEs served by the serving access point, there might be scenarios where the UE is not enabled to recover the original signal if using a sampling frequency that is lower than the Nyquist frequency, unless some other measures are taken.

Fig. 2 is a schematic diagram illustrating a communication network 100 where embodiments presented herein can be applied. The communications network 100 comprises network nodes 200a, 200b each configured to provide network access to UEs 300a, 300b, 300c, 3ood over wireless links 160a, 160b, 160c, i6od in a respective service region 150a, 150b via access points (APs) 140a, 140b. In the illustrative example of Fig. 2, network node 200a is assumed to serve UEs 300a, 300b via AP 140a in service region 150a, whilst network node 200b is assumed to serve UEs 300c, 3ood via AP 140b in service region 150b. In some examples the network nodes 200a, 200b are replaced by a common network node configured to provide network access in two or more such service regions. The service regions 150a, 150b collectively form an access network. The network nodes 200a, 200b are operatively connected to a service network 130, such as the Internet, via a core network 120. As the skilled person understands, each network node 200a, 200b could be operatively connected to more than one AP 140a, 140b.

Reference is now made to Fig. 3 illustrating a method for network-controlled UE sampling frequency as performed by the network node 200a according to an embodiment.

S106: The network node 200a assigns, to a first UE 300a, a first set of time-space- frequency (TSF) resources in a nominal frequency band. The nominal frequency band has the bandwidth B_o in a continuous-time spectrum.

In this respect, TSF resources are resources, such as resource elements or resource blocks, defined in a time, space, and frequency grid.

S110: The network node 200a instructs the first UE 300a to sample signals received by the first UE 300a and defined by the first set of TSF resources with a sampling frequency f_s, where f_s < 2B₀. The sampling frequency f_s is thus lower than the Nyquist sampling frequency. The network node 200a might instruct the first UE 300a via radio resource control (RRC) signalling, and/or via information, such as in a downlink control information (DCI) element, sent on a downlink control channel, such as on a physical downlink control channel (PDCCH).

S112: The network node 200a assigns, to a second UE 300b, a second set of TSF resources in the nominal frequency band B_o. The second set of TSF resources are non-overlapping with the first set of TSF resources in a discrete-time spectrum when the first set of TSF resources is sampled with the sampling frequency f_s.

S114: The network node 200a simultaneously transmits the signals defined by the first set of TSF resources towards the first UE 300a and signals defined by the second set of TSF resources towards the second UE 300b.

In this respect, that the signals are simultaneously transmitted implies that at least some of the first set of TSF resources and the second set of TSF resources are time- wise overlapping. In this respect, the first set of TSF resources and the second set of TSF resources might be fully overlapping in time or only partly overlapping in time. Further in this respect, the first set of TSF resources and the second set of TSF resources might be provided in a radio frame, a sub-frame, a time slot, or even a single orthogonal frequency-division multiplexing (OFDM) symbol. Correspondingly, the first set of TSF resources and the second set of TSF resources might time-wise overlap from as long as at least a complete frame to as short as a single OFDM symbol. In some examples, the TSF resources assigned to the second UE 300b and the TSF resources assigned to the first UE 300a are thus partly, but not fully, overlapping and might be relate to different time slots within one and the same radio frame. That is, the signals are simultaneously transmitted on a per radio frame basis but not necessarily in a per time slot basis within the radio frame. This enables a group of UEs (for example including the first UE 300a) with low service requirements to reduce their power consumption (by operating with a lower sampling rate) while another group of UEs (for example including the second UE 300b) with higher service requirements is enabled to operate utilizing the full bandwidth (most of the time).

In this way, the network node 200a instructs the first UE 300a to use under-sampling (i.e., to use a sampling frequency f_s, where f_s < 2B₀), and ensures that transmission to the second UE 300b does not cause aliasing when the first UE 300a performs sampling of its received signals.

Embodiments relating to further details of network-controlled UE sampling frequency as performed by the network node 200a will now be disclosed.

In some examples, the first set of TSF resources are assigned in a first subband B_± of the nominal frequency band. In such examples, 2B_± < f_s < 2B₀.

In some aspects, the network node 200a assigns resources to the second UE 300b at locations in the nominal frequency band such that no harmful aliasing at UEs 300a in a first UE set occurs, i.e., such that the UEs in the first UE set can reconstruct their received signals without distortion. This corresponds to embodiments where, according to a frequency component of the second set of TSF resources, the second set of TSF resources is assigned in a second subband B₂ of the nominal frequency band B_o in the continuous-time spectrum, and where the second subband B₂ is nonoverlapping with the first subband B .

Consider, without loss of generality, a setup where UE 300a and UE 300b are to receive respective signals simultaneously transmitted by a serving network node. UE 300a and UE 300b are assigned respective TSF resources in the same nominal frequency band. UE 300a is configured to sample received signals with a sampling frequency f_s, where f_s < 2B₀ and thus to under-sample its received signals. UE 300b is assigned TSF resources such that no harmful aliasing occurs at UE 300a.

A non-limiting numerical example will demonstrate one way to implement this with reference to Fig. 4 and Fig. 5. In the example, the nominal frequency band is 10 GHz wide. According to Fig. 4, in Fig. 4(a) UE 300a is assigned TSF resources according to the continuous-time signal spectrum 410a whereas UE 300b is assigned TSF resources according to the continuous-time signal spectrum 410b. For the given numerical values, the nominally required sampling frequency for UE 300a would be 18 GHz (since the highest allocated frequency in the continuous-time signal spectrum 410a is 9 GHz). But together, the UE 300a and UE 300b occupy only one third of the 10 GHz wide nominal frequency band. Therefore, under-sampling with a factor up to a third could be possible for UE 300a. Yet, performing such under-sampling at UE 300a (where UE 300a thus uses a sampling frequency f_s = 6 GHz) without prior analog filtering or any other anti-aliasing countermeasures would result in a discretetime signal spectrum 420a for UE 300a, which thus suffers from aliasing, as in Fig. 4(b), due to the discrete-time signal spectrum 420b for UE 300b. UE 300a is therefore not able to decode its signal. However, such aliasing can be avoided by frequency-wise re-assigning the TSF resources for UE 300b as shown in Fig. 5. In Fig. 5(a) UE 300a is assigned TSF resources according to the continuous-time signal spectrum 510a whereas UE 300b is assigned TSF resources according to the continuous-time signal spectrum 510b. The continuous-time signal spectrum 510a is thus the same as the continuous-time signal spectrum 410a. UE 300a is configured to under-sample in the same way as in Fig. 4, and thus to use a sampling frequency f_s = 6 GHz. As shown in Fig. 5(b), the re-assigning of the TSF resources for UE 300b results in the discrete-time signal spectrum 530a for UE 300a and the discrete-time signal spectrum 530b for UE 300b. Hence, aliasing does not occur and the signal for UE 300a is recoverable. In some aspects, the network node performs transmit beamforming in such a way that substantially no power transmitted towards any other UEs reaches the first UE set. This corresponds to embodiments where, according to a space component of the second set of TSF resources, the second set of TSF resources are assigned to be transmitted using a spatial beamformer, and where the spatial beam former is selected for the first set of TSF resources to lay in a null-space of the spatial beamformer.

In this respect, interference suppressing beamforming (such as zero-forcing) can be used to ensure that transmission of wideband signals towards UEs in a third UE set does not create aliasing interference for the first UE set. If the AP 140a, 140b is equipped with an antenna array configured for massive multiple-input multipleoutput (MIMO) communication, or the like, it is possible to ensure that no interference from transmissions targeting the third UE set reaches the first UE set and hence that no aliasing effects occur for the first UE set.

In some aspects, the network node 200a prioritizes creating null-spaces for UEs 300a that are under-sampling. Hence, in some embodiments, signals defined by a third set of TSF resources assigned a third UE are to be simultaneously transmitted with the signals defined by the second set of TSF resources, and selecting the spatial beamformer for the first set of TSF resources to lay in the null-space of the spatial beamformer is prioritized over selecting the spatial beamformer for the third set of TSF resources to lay in the null-space of the spatial beamformer. It is here implied that the third UE is not under-sampling.

In some aspects, the network node 200a negotiates with network nodes 200b serving neighbouring service regions which respective TSF resources to be used for serving UEs in the service region of the network node 200a and in the neighbouring service region. In particular, in some embodiments, the network node 200a serves the first UE 300a and the second UE 300b in a first service region 150a, and the network node 200a is configured to perform (optional) step S108.

S108: The network node 200a requests a network node 200b serving a third UE 300c, 3ood in a second service region 150b neighboring the first service region 150a to, to the third UE 300c, 3ood, avoid assigning TSF resources that overlap with the first set of TSF resources in the discrete-time spectrum when the first set of TSF resources is sampled with the sampling frequency f_s.

The network node might thus request a network node serving a neighbouring service region to not schedule any transmissions in the parts of the nominal frequency band that would cause distortion for the first UE set. The result of such a negotiation may be that neighboring network nodes agree to, at least for some period of time, reduce the transmission bandwidth of their respective served UEs.

It is envisioned that different UEs served by one and the same network node might have different capabilities. Whether a given UE 300a is to be instructed or not to use under-sampling might thus depend on capabilities of the UE 300a and/or service requirements of the UE 300a. Therefore, in some aspects, the network node inquiries its served UEs for its capabilities. In particular, in some embodiments, the first UE 300a is part of a first UE set, and the network node 200a is configured to perform (optional) step S102.

S102: The network node 200a receives information of UE capabilities and/or service requirements from UEs 300a, 300b served by the network node 200a. Which of the UEs 300a, 300b to be included in the first UE set is determined based on the received information.

For example, some UEs might be equipped with a tunable bandpass filter that can be activated to limit the bandwidth in which the sampling is performed before performing any under-sampling of received signals. Hence, in some embodiments, the UE capabilities pertain to whether the UEs 300a, 300b are capable of sampling signals with the sampling frequency f_s or not, and where the first UE set only comprises UEs being capable of sampling signals with the sampling frequency f_s. Further aspects of this will be disclosed below in conjunction with the description of Fig. 8.

Further in this respect, depending on the deployment scenario, density of APs, reservations and reuses of TSF resources in each service region, etc. interference might be caused by APs controlled by another network node or from other systems (in case of unlicensed operation). This interference could result in distortion due to aliasing if the first UE set performs under-sampling (by using the sampling frequency f_s as instructed). This distortion might not be controllable by assignment of TSF resources or beamforming at the network node. Therefore, in some aspects the network node is configured to inquiry any served UE to measure how much interference (from out-of-cell or out-of-system) there is, for example outside its intended subband, in order for the network node to gauge how much distortion there would be due to out-of-cell or out-of-system interference because of aliasing if any under-sampling is to be performed by any of the served UEs. If the level of interference exceeds a threshold value for any served UE, then this UE should not be instructed to perform any under-sampling, at least not unless this UE is equipped with a tunable bandpass filter that can be activated first. In particular, in some embodiments, the UE capabilities pertain to whether the UEs 300a, 300b have a tunable bandpass filter or not, and where the first UE set comprises at least some of the UEs 300a that have the tunable bandpass filter. UEs having the capability to suppress aliasing distortion when performing under-sampling require less protection in terms of advanced transmission beamforming processing or reduced bandwidth scheduling from the network side.

In some aspects, under-sampling is only suitable for signals belonging to services with comparatively low quality of service. Therefore, in some embodiments, the service requirements pertain to whether the UEs 300a, 300b require a quality of service above or below a quality threshold value, and where the first UE set only comprises UEs 300a for which the quality of service is below the quality threshold value.

In some aspects, the UE 300a might itself, for example due to battery drainage, or other reasons, request the network node 20 to use under-sampling. In particular, in some embodiments, the network node 200a is configured to perform (optional) step S104.

S104: The network node 200a receives, from UEs 300a served by the network node 200a, a request for operation in a reduced bandwidth and/or for operation using a reduced sampling frequency. The first UE set comprises at least some UEs 300a from which such a request is received. In some aspects, the network node uses a very robust modulation and coding scheme (e.g. Quadrature Phase Shift Keying (QPSK) and very low channel encoding rate r = k I n, such as r = i/io) to compensate for the additional interference that gets folded into the signals as received by the first UE set.

In some aspects, a set of APs are located in an environment that is shielded from outside interference (e.g. in an indoor factory operating at a high frequency band e.g. 100-300 GHz). In that case the sampling frequency for the first UE set might be controlled by a network node in the form of a central entity that takes the traffic of all APs in the isolated environment into account. Hence, in some embodiments, the sampling frequency f_s is a function of aggregated traffic volume handled by the network node 200a, and where the sampling frequency f_s is set to decrease with decreased aggregated traffic volume and to increase with increased aggregated traffic volume. That is, as the aggregated traffic decreases, this allows the sampling frequency f_s to also decrease, and vice versa.

In some scenarios the network may not have the excess capacity required to support that some UEs operate with reduced sampling frequency. However, since the traffic in most networks is highly dependent on the time of day it may still be possible to support communication over a reduced bandwidth and to use reduced sampling frequency operation for most UEs most of the time. Hence, in some embodiments, the sampling frequency f_s is a function of time of day, and where the sampling frequency f_s is set to be lower in a first time interval (such as between 03:00 AM and 06:00 AM) than in a second time interval (such as between 11:00 AM and 11:00 PM). In some network deployments the amount of aggregated traffic (e.g. number of communicated bits between the network node 200a and its served UEs 300a, 300b, or the number of connected UEs per network node) is typically around 10% of the daily peak value some-time during the night hours. This is illustrated in Fig. 6. In Fig. 6(a) is illustrated how the aggregated traffic (in terms of number of active served UEs) for the network node 200a varies over time. In Fig. 6(b) is illustrated how the sampling frequency can be lowered over time with respect to the variation of aggregated traffic in Fig. 6(a).

Reference is now made to Fig. 7 illustrating a method for network-controlled UE sampling frequency as performed by the UE 300a according to an embodiment. S206: The UE 300a receives instructions from a network node 200a serving the UE 300a to sample signals defined by a first set of TSF resources with a sampling frequency f_s < 2B₀, where B_o represents a bandwidth of a nominal frequency band in a continuous-time spectrum.

S208: The UE 300a receives the signals defined by the first set of TSF resources.

S210: The UE 300a samples the received signals with the sampling frequency f_s.

Embodiments relating to further details of network-controlled UE sampling frequency as performed by the UE 300a will now be disclosed.

As disclosed above, in some aspects the UE 300a reports its capabilities and/or service requirements to the network node 200a. Hence, in some embodiments, the UE 300a is configured to perform (optional) step S202.

S202: The UE 300a sends information of UE capabilities and/or service requirements to the network node 200a.

As disclosed above, in some embodiments, the UE capabilities pertain to that the UE 300a is capable of sampling signals with the sampling frequency f_s. As disclosed above, in some embodiments, the UE capabilities pertain to that the UE 300a has a tunable bandpass filter. The tunable bandpass filter is then activated when the UE 300a is receiving the signals in S206. As disclosed above, in some embodiments, the service requirements pertain to that the UE 300a only requires a quality of service below a quality threshold value.

As disclosed above, in some aspects the UE 300a sends an explicit request for operation in a reduced bandwidth and/or with a reduced sampling frequency. Hence, in some embodiments, the UE 300a is configured to perform (optional) step S204.

S204: The UE 300a sends, to the network node 200a, a request for operation in a reduced bandwidth and/ or for operation using a reduced sampling frequency.

This could, for example, be the case where the battery level of the UE 300a is below some threshold value, where the battery level of the 300a is reducing faster than some threshold reduction factor, and/or where the UE 300a is receiving data of a service where the quality of service is lower than a quality threshold. However, the UE 300a might also for other reasons save power and thus request to operate in a reduced bandwidth and/ or to operate using a reduced sampling frequency.

One particular embodiment for network-controlled UE sampling frequency based on at least some of the above disclosed embodiments will now be disclosed in detail with reference to the signalling diagram of Fig. 8.

In S301 the UE 300a connects to the network node in a normal fashion (e.g., by reading system information and performing a random access procedure). In S302 the UE 300a reports its capabilities and/or service requirements to the network node 200a. Example of capabilities and/or service requirements have been listed above. If the service requirements are very much lower than what the nominal frequency band can support, then the UE 300a may benefit from operating with a reduced sampling frequency in order to reduce its energy consumption and extend its battery life. The UE 300a might in S302 further send an explicit request for operation with a reduced bandwidth and/or a reduced sampling frequency. The network node 200a in S303 determines the feasibility of this request e.g. by considering the aggregated traffic volume (e.g. if the aggregated traffic is low then the bandwidth for the UE 300a can be reduced and/or all its served UEs 300a, 300b can operate with a lower sampling frequency), and/or if the spatial separation between the served UEs 300a, 300b is favorable such that efficient interference suppression beamforming will be possible. If the request for reduced sampling frequency is feasible the network node 200a in S304 configures the UE 300a with a reduced sampling frequency. The UE 300a in S305 uses the reduced sampling frequency when receiving signals from the network node 200a. At some later point in time, the conditions may have changed, and the network node 200a therefore in S306 determines that it is no longer feasible for the UE 300a to use the configured reduced sampling frequency. The network node 200 therefore in S307 reconfigures the sampling frequency of the UE back to the (normal) Nyquist sampling frequency. The UE 300a in S308 uses the (normal) Nyquist sampling frequency when receiving signals from the network node 200a.

In summary terms, at least some of the herein disclosed methods are based on the following. The network node 200a transmits first signals to a first UE 300a. The first UE 300a is configured to use a sampling frequency lower than the Nyquist sampling frequency when sampling the received first signals. The network node 200a transmits second signals to a second UE 300b. The transmissions of the first signals and the second signals are frequency multiplexed over the same time frame.

Fig. 9 schematically illustrates, in terms of a number of functional units, the components of a network node 200a according to an embodiment. Processing circuitry 210 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product 1310a (as in Fig. 13), e.g. in the form of a storage medium 230. The processing circuitry 210 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

Particularly, the processing circuitry 210 is configured to cause the network node 200a to perform a set of operations, or steps, as disclosed above. For example, the storage medium 230 may store the set of operations, and the processing circuitry 210 maybe configured to retrieve the set of operations from the storage medium 230 to cause the network node 200a to perform the set of operations. The set of operations maybe provided as a set of executable instructions. Thus the processing circuitry 210 is thereby arranged to execute methods as herein disclosed.

The storage medium 230 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.

The network node 200a may further comprise a communications interface 220 for communications with other entities, functions, nodes, and devices, as in the communication network 100. As such the communications interface 220 may comprise one or more transmitters and receivers, comprising analogue and digital components.

The processing circuitry 210 controls the general operation of the network node 200a e.g. by sending data and control signals to the communications interface 220 and the storage medium 230, by receiving data and reports from the communications interface 220, and by retrieving data and instructions from the storage medium 230. Other components, as well as the related functionality, of the network node 200a are omitted in order not to obscure the concepts presented herein.

Fig. io schematically illustrates, in terms of a number of functional modules, the components of a network node 200a according to an embodiment. The network node 200a of Fig. io comprises a number of functional modules; a (first) assign module 2ioc configured to perform step Sio6, an instruct module 2ioe configured to perform step Sno, a (second) assign module 2iof configured to perform step S112, and a transmit module 210g configured to perform step S114. The network node 200a of Fig. 10 may further comprise a number of optional functional modules, such as any of a (first) receive module 210a configured to perform step S102, a (second) receive module 210b configured to perform step S104, and a request module (2iod) configured to perform step S108. In general terms, each functional module 210a: 210g may be implemented in hardware or in software. Preferably, one or more or all functional modules 210a: 210g may be implemented by the processing circuitry 210, possibly in cooperation with the communications interface 220 and/or the storage medium 230. The processing circuitry 210 may thus be arranged to from the storage medium 230 fetch instructions as provided by a functional module 2ioa:2iog and to execute these instructions, thereby performing any steps of the network node 200a as disclosed herein.

The network node 200a maybe provided as a standalone device or as a part of at least one further device. For example, the network node 200a maybe provided in a node of the access network or in a node of the core network. Alternatively, functionality of the network node 200a may be distributed between at least two devices, or nodes. These at least two nodes, or devices, may either be part of the same network part (such as the access network or the core network) or may be spread between at least two such network parts. In general terms, instructions that are required to be performed in real time maybe performed in a device, or node, operatively closer to the service region than instructions that are not required to be performed in real time. Thus, a first portion of the instructions performed by the network node 200a maybe executed in a first device, and a second portion of the instructions performed by the network node 200a may be executed in a second device; the herein disclosed embodiments are not limited to any particular number of devices on which the instructions performed by the network node 200a may be executed. Hence, the methods according to the herein disclosed embodiments are suitable to be performed by a network node 200a residing in a cloud computational environment. Therefore, although a single processing circuitry 210 is illustrated in Fig. 9 the processing circuitry 210 maybe distributed among a plurality of devices, or nodes. The same applies to the functional modules 210a: 210g of Fig. 10 and the computer program 1320a of Fig. 13.

Fig. 11 schematically illustrates, in terms of a number of functional units, the components of a UE 300a according to an embodiment. Processing circuitry 310 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product 1310b (as in Fig. 13), e.g. in the form of a storage medium 330. The processing circuitry 310 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

Particularly, the processing circuitry 310 is configured to cause the UE 300a to perform a set of operations, or steps, as disclosed above. For example, the storage medium 330 may store the set of operations, and the processing circuitry 310 maybe configured to retrieve the set of operations from the storage medium 330 to cause the UE 300a to perform the set of operations. The set of operations maybe provided as a set of executable instructions. Thus the processing circuitry 310 is thereby arranged to execute methods as herein disclosed.

The storage medium 330 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.

The UE 300a may further comprise a communications interface 320 for communications with other entities, functions, nodes, and devices, as in the communication network 100. As such the communications interface 320 may comprise one or more transmitters and receivers, comprising analogue and digital components.

The processing circuitry 310 controls the general operation of the UE 300a e.g. by sending data and control signals to the communications interface 320 and the storage medium 330, by receiving data and reports from the communications interface 320, and by retrieving data and instructions from the storage medium 330. Other components, as well as the related functionality, of the UE 300a are omitted in order not to obscure the concepts presented herein.

Fig. 12 schematically illustrates, in terms of a number of functional modules, the components of a UE 300a according to an embodiment. The UE 300a of Fig. 12 comprises a number of functional modules; a (first) receive module 310c configured to perform step S206, a (second) receive module 3iod configured to perform step S208, and a sample module (3ioe) configured to perform step S210. The UE 300a of Fig. 12 may further comprise a number of optional functional modules, such as any of a (first) send module 310a configured to perform step S202, and a (second) send module 310b configured to perform step S204. In general terms, each functional module 3ioa:3ioe maybe implemented in hardware or in software. Preferably, one or more or all functional modules 3ioa:3ioe maybe implemented by the processing circuitry 310, possibly in cooperation with the communications interface 320 and/or the storage medium 330. The processing circuitry 310 may thus be arranged to from the storage medium 330 fetch instructions as provided by a functional module 3ioa:3ioe and to execute these instructions, thereby performing any steps of the UE 300a as disclosed herein.

Fig. 13 shows one example of a computer program product 1310a, 1310b comprising computer readable means 1330. On this computer readable means 1330, a computer program 1320a can be stored, which computer program 1320a can cause the processing circuitry 210 and thereto operatively coupled entities and devices, such as the communications interface 220 and the storage medium 230, to execute methods according to embodiments described herein. The computer program 1320a and/or computer program product 1310a may thus provide means for performing any steps of the network node 200a as herein disclosed. On this computer readable means 1330, a computer program 1320b can be stored, which computer program 1320b can cause the processing circuitry 310 and thereto operatively coupled entities and devices, such as the communications interface 320 and the storage medium 330, to execute methods according to embodiments described herein. The computer program 1320b and/or computer program product 1310b may thus provide means for performing any steps of the UE 300a as herein disclosed. In the example of Fig. 13, the computer program product 1310a, 1310b is illustrated as an optical disc, such as a CD (compact disc) or a DVD (digital versatile disc) or a Blu-Ray disc. The computer program product 1310a, 1310b could also be embodied as a memory, such as a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM) and more particularly as a non-volatile storage medium of a device in an external memory such as a USB (Universal Serial Bus) memory or a Flash memory, such as a compact Flash memory. Thus, while the computer program 1320a, 1320b is here schematically shown as a track on the depicted optical disk, the computer program 1320a, 1320b can be stored in any way which is suitable for the computer program product 1310a, 1310b.

The inventive concept has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended patent claims.

Claims

1. A method for network-controlled user equipment, UE, sampling frequency, the method being performed by a network node (200a), the method comprising: assigning (S106), to a first UE (300a), a first set of time-space-frequency, TSF, resources in a nominal frequency band with bandwidth B_o in a continuous-time spectrum; instructing (S110) the first UE (300a) to sample signals received by the first UE (300a) and defined by the first set of TSF resources with a sampling frequency f_s, where f_s < 2B₀; assigning (S112), to a second UE (300b), a second set of TSF resources in the nominal frequency band B_o, wherein the second set of TSF resources are nonoverlapping with the first set of TSF resources in a discrete-time spectrum when the first set of TSF resources is sampled with the sampling frequency f_s; simultaneously transmitting (S114) the signals defined by the first set of TSF resources towards the first UE (300a) and signals defined by the second set of TSF resources towards the second UE (300b).

2. The method according to claim 1, wherein the first TSF resources are assigned in a first subband B_± of the nominal frequency band B_o, wherein, according to a frequency component of the second set of TSF resources, the second set of TSF resources is assigned in a second subband B₂ of the nominal frequency band B_o in the continuous-time spectrum, and wherein the second subband B₂ is non-overlapping with the first subband B .

3. The method according to any preceding claim, wherein, according to a space component of the second set of TSF resources, the second set of TSF resources are assigned to be transmitted using a spatial beamformer, and wherein the spatial beam former is selected for the first set of TSF resources to lay in a null-space of the spatial beamformer.

4. The method according to claim 3, wherein signals defined by a third set of TSF resources assigned a third UE are to be simultaneously transmitted with the signals defined by the second set of TSF resources, and wherein selecting the spatial beamformer for the first set of TSF resources to lay in the null-space of the spatial beamformer is prioritized over selecting the spatial beamformer for the third set of TSF resources to lay in the null-space of the spatial beamformer.

5. The method according to any preceding claim, wherein the network node (200a) serves the first UE (300a) and the second UE (300b) in a first service region (150a), and wherein the method further comprises: requesting (S108) a network node (200b) serving a third UE (300c, 3ood) in a second service region (150b) neighboring the first service region (150a) to, to the third UE (300c, 3ood), avoid assigning TSF resources that overlap with the first set of TSF resources in the discrete-time spectrum when the first set of TSF resources is sampled with the sampling frequency f_s.

6. The method according to any preceding claim, wherein the first UE (300a) is part of a first UE set, and wherein the method further comprises: receiving (S102) information of UE capabilities and/or service requirements from UEs (300a, 300b) served by the network node (200a), and wherein which of the UEs (300a, 300b) to be included in the first UE set is determined based on the received information.

7. The method according to claim 6, wherein the UE capabilities pertain to whether the UEs (300a, 300b) are capable of sampling signals with the sampling frequency f_s or not, and wherein the first UE set only comprises UEs being capable of sampling signals with the sampling frequency f_s.

8. The method according to claim 6, wherein the UE capabilities pertain to whether the UEs (300a, 300b) have a tunable bandpass filter or not, and wherein the first UE set comprises at least some of the UEs (300a) that have the tunable bandpass filter.

9. The method according to claim 6, wherein the service requirements pertain to whether the UEs (300a, 300b) require a quality of service above or below a quality threshold value, and wherein the first UE set only comprises UEs (300a) for which the quality of service is below the quality threshold value. io. The method according to any preceding claim, wherein the first UE (300a) is part of a first UE set, wherein the method further comprises: receiving (S104), from UEs (300a) served by the network node (200a), a request for operation in a reduced bandwidth and/or for operation using a reduced sampling frequency, and wherein the first UE set comprises at least some UEs (300a) from which the request is received.

11. The method according to any preceding claim, wherein the sampling frequency f_s is a function of aggregated traffic volume handled by the network node (200a), and wherein the sampling frequency f_s is set to decrease with decreased aggregated traffic volume and to increase with increased aggregated traffic volume.

12. The method according to any preceding claim, wherein the sampling frequency f_s is a function of time of day, and wherein the sampling frequency f_s is set to be lower in a first time interval than in a second time interval.

13. The method according to any preceding claim, wherein, time-wise, there are fewer first set of TSF resources than second set of TSF resources.

14. A method for network-controlled user equipment, UE, sampling frequency, the method being performed by a UE (300a), the method comprising: receiving (S206) instructions from a network node (200a) serving the UE (300a) to sample signals defined by a first set of time-space-frequency, TSF, resources with a sampling frequency f_s < 2B₀, where B_o represents a bandwidth of a nominal frequency band in a continuous-time spectrum; receiving (S208) the signals defined by the first set of TSF resources; and sampling (S210) the received signals with the sampling frequency f_s.

15. The method according to claim 14, wherein the method further comprises: sending information (S202) of UE capabilities and/or service requirements to the network node (200a). 16. The method according to claim 15, wherein the UE capabilities pertain to that the UE (300a) is capable of sampling signals with the sampling frequency f_s.

17. The method according to claim 14, wherein the UE capabilities pertain to that the UE (300a) has a tunable bandpass filter, and wherein the tunable bandpass filter is activated when receiving the signals.

18. The method according to claim 14, wherein the service requirements pertain to that the UE (300a) only requires a quality of service below a quality threshold value.

19. The method according to any of claims 14 to 18, wherein the method further comprises: sending (S204), to the network node (200a), a request for operation in a reduced bandwidth and/ or for operation using a reduced sampling frequency.

20. A network node (200a) for network-controlled user equipment, UE, sampling frequency, the network node (200a) comprising processing circuitry (210), the processing circuitry being configured to cause the network node (200a) to: assign, to a first UE (300a), a first set of time-space-frequency, TSF, resources in a nominal frequency band with bandwidth B_o in a continuous-time spectrum; instruct the first UE (300a) to sample signals received by the first UE (300a) and defined by the first set of TSF resources with a sampling frequency f_s, where f_s < 2B₀; assign, to a second UE (300b), a second set of TSF resources in the nominal frequency band B_o, wherein the second set of TSF resources are non-overlapping with the first set of TSF resources in a discrete-time spectrum when the first set of TSF resources is sampled with the sampling frequency f_s; simultaneously transmit the signals defined by the first set of TSF resources towards the first UE (300a) and signals defined by the second set of TSF resources towards the second UE (300b).

21. A network node (200a) for network-controlled user equipment, UE, sampling frequency, the network node (200a) comprising: an assign module (210c) configured to assign, to a first UE (300a), a first set of time-space-frequency, TSF, resources in a nominal frequency band with bandwidth B_o in a continuous-time spectrum; an assign module (2ioe) configured to instruct the first UE (300a) to sample signals received by the first UE (300a) and defined by the first set of TSF resources with a sampling frequency f_s, where f_s < 2B₀; an assign module (2iof) configured to assign, to a second UE (300b), a second set of TSF resources in the nominal frequency band B_o, wherein the second set of TSF resources are non-overlapping with the first set of TSF resources in a discrete-time spectrum when the first set of TSF resources is sampled with the sampling frequency fs,- a transmit module (210g) configured to simultaneously transmit the signals defined by the first set of TSF resources towards the first UE (300a) and signals defined by the second set of TSF resources towards the second UE (300b).

22. The network node (200a) according to claim 20 or 21, further being configured to perform the method according to any of claims 2 to 13.

23. A user equipment, UE, (300a) for network-controlled UE sampling frequency, the UE (300a) comprising processing circuitry (310), the processing circuitry being configured to cause the UE (300a) to: receive instructions from a network node (200a) serving the UE (300a) to sample signals defined by a first set of time-space-frequency, TSF, resources with a sampling frequency f_s < 2B₀, where B_o represents a bandwidth of a nominal frequency band in a continuous-time spectrum; receive the signals defined by the first set of TSF resources; and sample the received signals with the sampling frequency f_s.

24. A user equipment, UE, (300a) for network-controlled UE sampling frequency, the UE (300a) comprising: a receive module (310c) configured to receive instructions from a network node (200a) serving the UE (300a) to sample signals defined by a first set of time-space- frequency, TSF, resources with a sampling frequency f_s < 2B₀, where B_o represents a bandwidth of a nominal frequency band in a continuous-time spectrum; a receive module (3iod) configured to receive the signals defined by the first set of TSF resources; and a sample module (3ioe) configured to sample the received signals with the sampling frequency f_s.

25. The UE (300a) according to claim 23 or 24, further being configured to perform the method according to any of claims 15 to 19.

26. A computer program (1320a) for network-controlled user equipment, UE, sampling frequency, the computer program comprising computer code which, when run on processing circuitry (210) of a network node (200a), causes the network node (200a) to: assign (S106), to a first UE (300a), a first set of time-space-frequency, TSF, resources in a nominal frequency band with bandwidth B_o in a continuous-time spectrum; instruct (S110) the first UE (300a) to sample signals received by the first UE (300a) and defined by the first set of TSF resources with a sampling frequency f_s, where f_s < 2B₀; assign (S112), to a second UE (300b), a second set of TSF resources in the nominal frequency band B_o, wherein the second set of TSF resources are nonoverlapping with the first set of TSF resources in a discrete-time spectrum when the first set of TSF resources is sampled with the sampling frequency f_s; simultaneously transmit (S114) the signals defined by the first set of TSF resources towards the first UE (300a) and signals defined by the second set of TSF resources towards the second UE (300b). •2TJ. A computer program (1320b) for network-controlled user equipment, UE, sampling frequency, the computer program comprising computer code which, when run on processing circuitry (310) of a UE (300a), causes the UE (300a) to: receive (S206) instructions from a network node (200a) serving the UE (300a) to sample signals defined by a first set of time-space-frequency, TSF, resources with a sampling frequency f_s < 2B₀, where B_o represents a bandwidth of a nominal frequency band in a continuous-time spectrum; receive (S208) the signals defined by the first set of TSF resources; and sample (S210) the received signals with the sampling frequency f_s. 28. A computer program product (1310a, 1310b) comprising a computer program

(1320a, 1320b) according to at least one of claims 26 and 27, and a computer readable storage medium (1330) on which the computer program is stored.