WO2018236262A1

WO2018236262A1 - A transmitter, a receiver and methods therein for enabling measurements based on reference signals in one or more receiver beams in a wireless communications network

Info

Publication number: WO2018236262A1
Application number: PCT/SE2018/050473
Authority: WO
Inventors: Karl Werner; Ali ZAIDI; Stephen Grant; Mattias Frenne
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2017-06-22
Filing date: 2018-05-07
Publication date: 2018-12-27

Abstract

A method performed in a transmitter (110) for enabling measurements based on reference signals in one or more receiver beams at a receiver (121) in a wireless communications system is provided. The transmitter (110) determines a number of symbols to use for the reference signals that are to be transmitted to the receiver (121) using one or more transmitter beams based on information indicating a time period needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver (121). A transmitter (110) for enabling measurements based on reference signals in one or more receiver beams at a receiver (121) in a wireless communications system is also provided. Further, a receiver (121) and method therein for enabling measurements based on reference signals from a transmitter (110) in a wireless communications system in one or more receiver beams are also provided.

Description

A TRANSMITTER, A RECEIVER AND METHODS THEREIN FOR ENABLING

MEASUREMENTS BASED ON REFERENCE SIGNALS IN ONE OR MORE RECEIVER BEAMS IN A WIRELESS COMMUNICATIONS NETWORK TECHNICAL FIELD

Embodiments herein relate to beamforming in a wireless communications network. In particular, embodiments herein relate to a transmitter and a method therein for enabling measurements based on reference signals in one or more receiver beams at a receiver in a wireless communications network. Embodiments herein also relate to a receiver and method therein for enabling measurements based on reference signals in one or more receiver beams in a wireless communications network.

BACKGROUND

In today's wireless communications networks a number of different technologies are used, such as New Radio (NR), Long Term Evolution (LTE), LTE-Advanced,

Wideband Code Division Multiple Access (WCDMA), Global System for Mobile

communications/Enhanced Data rate for GSM Evolution (GSM/EDGE), Worldwide Interoperability for Microwave Access (WMax), or Ultra Mobile Broadband (UMB), just to mention a few possible technologies for wireless communication. A wireless

communications network comprises radio base stations providing radio coverage over at least one respective geographical area forming a cell. The cell definition may also incorporate frequency bands used for transmissions, which means that two different cells may cover the same geographical area but using different frequency bands. Wireless devices, also referred to herein as User Equipments, UEs, mobile stations, and/or wireless terminals, are served in the cells by the respective radio base station and are communicating with respective radio base station. The wireless devices transmit data over an air or radio interface to the radio base stations in uplink, UL, transmissions and the radio base stations transmit data over an air or radio interface to the wireless devices in downlink, DL, transmissions.

In NR, it is envisaged to employ antenna arrays with analogue beamforming or hybrid analogue/digital beamforming. With such array structures, beam-sweeping may be necessary in order to find which precoder/beamformer to use for a transmission. A beam sweeping procedure normally start in that a transmitter transmitting a reference signal using a sequence of precoders/beamformers. In this case, depending on the antenna array, multiple precoders may for example be sounded concurrently, i.e. tested in sequence. Then, a receiver may report the signal quality experienced for each sounded or tested precoder/beamformer. The receiver may alternatively also sound or test a subset of the precoders/beamformers. In case the receiver is also equipped with an antenna array which may use analogue beamforming, then the receiver beam may also need to be swept. Here, it is required that the transmission precoder is constant and does not change during the receiver beam sweep. Several options for the design and transmission of the reference signal, i.e. a signal comprising reference symbol information, such as, for example, Channel State-Information Reference Symbols, CSI-RS, to support beam sweeping exits today. One such option is to use a spread-spectrum multiple-access scheme, such as, Interleaved Frequency-Division Multiple Access, IFDMA. One advantage of using IFDMA is that it allows for a flexible number of receiver beams for a single transmit signal waveform.

Fig. 1 shows one example of how four (4) receiver beams may be tested using IFDMA based reference symbols. To the left, a time frequency grid of Resource Elements, REs, is illustrated, e.g. a OFDM symbol index may be on the x-axis, and subcarrier index on y-axis. N may here be a so-called comb repetition factor. In this case, N=4, which means that every forth subcarrier is used for CSI-RS, or equivalently that the time domain signal will have four repetitions within the symbol interval. To the right, the resulting time domain signal in one of the OFDM symbols, i.e. the second column in the left-most illustration, is illustrated. Thus, here, in particular, four (4) receiver beams are tested during an IFDMA reference symbol, e.g. a single CSI-RS transmission time unit, TTU. The single CSI-RS transmission time unit, TTU, in this case being the same as a reference OFDM symbol time, TREF. However, always transmitting CSI-RS for the maximum required time will lead to an unnecessarily high signalling overhead.

SUMMARY

An object of the invention may be to improve beamforming in a wireless communications network. According to a first aspect of embodiments herein, the object may be achieved by a method performed in a transmitter for enabling measurements based on reference signals in one or more receiver beams at a receiver in a wireless communications network. The transmitter determines a number of symbols to use for the reference signals that is to be transmitted to the receiver using one or more transmitter beams based on information indicating a time period needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver.

According to a second aspect of embodiments herein, the object may also be achieved by a transmitter for enabling measurements based on reference signals in one or more receiver beams at a receiver in a wireless communications network. The transmitter is to be configured to determine a number of symbols to use for the reference signals that is to be transmitted to the receiver using one or more transmitter beams based on information indicating a time period needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver.

According to a third aspect of embodiments herein, the object may be achieved by a method performed by a receiver for enabling measurements based on reference signals from a transmitter in a wireless communications network in one or more receiver beams. The receiver determines information indicating a time period needed for performing measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver. Also, the receiver transmits information indicating the time period to a transmitter in the wireless communications network.

According to a fourth aspect of embodiments herein, the object may also be achieved by a receiver for enabling measurements based on reference signals from a transmitter in a wireless communications network in one or more receiver beams. The receiver is configured to determine information indicating a time period needed for performing measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver. Also, the receiver is configured to transmit information indicating the time period to a transmitter in the wireless

communications network. According to a fifth aspect of the embodiments herein, computer programs are also provided configured to perform the methods described above. Further, according to a sixth aspect of the embodiments herein, carriers are also provided configured to carry the computer programs described above. Further possible features and benefits of this solution will become apparent from the detailed description below.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described in more detail in relation to the enclosed drawings, in which:

Fig. 1 is a schematic illustration depicting a transmission using IFDMA,

Fig. 2 is a schematic overview depicting embodiments of a transmitter and receiver in a wireless communications network,

Fig. 3 is a flow chart of embodiments of a method in a transmitter,

Fig. 4 is a flow chart of embodiments of a method in a receiver,

Fig. 5 is a signalling scheme depicting embodiments of a method in a transmitter and in a receiver,

Fig. 6 is another signalling scheme depicting embodiments of a method in a transmitter and in a receiver,

Fig. 7 is a block diagram depicting embodiments of a transmitter,

Fig. 8 is a block diagram depicting embodiments of a receiver,

Fig. 9 is another block diagram depicting embodiments of a transmitter, and

Fig. 10 is another block diagram depicting embodiments of a receiver.

DETAILED DESCRIPTION

The figures herein are schematic and simplified for clarity, and they merely show details which are essential to the understanding of the embodiments presented herein, while other details have been left out. Throughout, the same reference numerals are used for identical or corresponding parts or steps.

Fig. 2 depicts a wireless communications network 100 in which embodiments herein may operate. In some embodiments, the wireless communications network 100 may be a radio communications network, such as, New Radio (NR) network. Although, the wireless communications network 100 is exemplified herein as an NR network, the wireless communications network 100 may also employ technology of any one of Long Term Evolution (LTE), LTE-Advanced, Wdeband Code Division Multiple Access

(WCDMA), Global System for Mobile communications/Enhanced Data rate for GSM Evolution (GSM/EDGE), Worldwide Interoperability for Microwave Access (WiMax), Ultra Mobile Broadband (UMB) or GSM, or any other similar network or system. The wireless communications network 100 may also be an Ultra Dense Network, UDN, which e.g. may transmit on millimetre-waves (mmW).

The wireless communications network 100 comprises a network node 110. The 5 network node 1 10 serves at least one cell 115. The network node 1 10 may correspond to any type of network node or radio network node capable of communicating with a wireless device and/or with another network node, such as, e.g. be a base station, a radio base station, eNB, eNodeB, a Home Node B, a Home eNode B, femto Base Station (BS), pico BS, etc., in the wireless communications network 100. Further examples of the network

10 node 110 may also be e.g. repeater, base station (BS), multi-standard radio (MSR) radio node such as MSR BS, eNodeB, network controller, radio network controller (RNC), base station controller (BSC), relay, donor node controlling relay, base transceiver station (BTS), access point (AP), transmission points, transmission nodes, a Remote Radio Unit (RRU), a Remote Radio Head (RRH), nodes in distributed antenna system (DAS), core

15 network node (e.g. MSC, MME, etc.), O&M, OSS, SON, positioning node (e.g. E-SMLC), MDT, etc.

In Fig. 2, a wireless device 121 is located within the cell 1 15. The wireless device 121 is configured to communicate within the wireless communications network 100 via the network node 1 10 over a radio link served by the network node 1 10. The wireless device

20 121 may refer to any type of wireless device or user equipment (UE) communicating with a network node and/or with another wireless device in a cellular, mobile or radio communication network or system. Examples of such wireless devices are mobile phones, cellular phones, Personal Digital Assistants (PDAs), smart phones, tablets, sensors equipped with a UE, Laptop Mounted Equipment (LME) (e.g. USB), Laptop

25 Embedded Equipments (LEEs), Machine Type Communication (MTC) devices, or

Machine to Machine (M2M) device, Customer Premises Equipment (CPE), target device, device-to-device (D2D) wireless device, wireless device capable of machine to machine (M2M) communication, etc.

Furthermore, although embodiments below are described with reference to Fig. 2,

30 this should not be construed as limiting to the embodiments herein, but merely as an example made for illustrative purposes. Although reference numerals below indicate that the transmitter is, or is comprised in, the network node 110 and that the receiver is, or is comprised in, the wireless device 121 , it should be noted that this is just one example and that the transmitter and the receiver may be located in any suitable device or apparatus

35 configured to operate within the wireless communications network 100. As part of the developing of the embodiments described herein, it has been realized that if more receiver beams are to be tested within the IFDMA reference symbol, then the measurement time for each receiver beam will become shorter. This will affect the radio link budget for the measurements. Generally, this means that the number of receiver beams that may be tested during a given time slot, such as, a IFDMA RS, CSI- RS TTU or other transmission time units, will depend on the effective channel

experienced by the receiver. The latter may also take into account the transmitter precoder/beamformer.

It has also been realized that another factor that may affect the minimum measurement time for a single receiver beam is the type of measurement that need to be done by the receiver. For example, if only the Reference Signal Received Power, RSPR, of a receiver beam needs to be measured, then less time is required than when, e.g. performing measurements of detailed CSI-RS. This means that the total measurement time that needs to be allocated for a receiver beam sweep, and thus the time interval for which the CSI-RS needs to be transmitted with a constant transmission

precoder/beamformer may depend on, for example, the number of receiver beams to be tested. The number of receiver beams to be tested may be specific to the receiver implementation. The total measurement time may also depend on the number of concurrent receiver beams that the receiver may evaluated. This may, for example, depend on the digital/analogue beamforming structure of the receiver. Further, the total measurement time may further depend on, for example, the channel conditions and the requested measurements by the transmitter.

This should be taken into account when performing a beam sweep procedure in a wireless communications network, since the alternative of always transmitting CSI-RS for the maximum required time will lead to an unnecessarily high signalling overhead.

This issue is addressed by embodiments described herein with reference to Figs. 3-8. The embodiment described herein proposes that the receiver signals, i.e. transmits, to the network an indication of the transmission time needed for the receiver beam sweep, for example, in the form of a time duration, a required number of IFDMA symbols, a number of repetitions, and/or a periodicity. This signalling could, for example, convey the number of required CSI-RS symbols, that is, the number of CSI-RS symbols over which the transmitter beam needs to stay constant for the receiver to be able to perform its beam measurements. It should be noted that while the embodiments described herein are relevant for the IFDMA CSI-RS signal structure, the embodiments described herein may also be used for other signal structures, such as, for example, those signal structures which depend on modifying OFDM symbol durations for the CSI-RS compared to data. An advantage of some of the embodiments described herein may be that they allow for a balanced allocation of resources to a receiver beam sweep, while still accommodating receivers with different capabilities. The embodiments herein may allow this without requiring detailed knowledge of the receiver capabilities on the network side. The latter may be desirable as it may reduce configuration and signalling complexity.

Example of embodiments of a method performed by a transmitter 1 10 for enabling measurements based on reference signals in one or more receiver beams at a receiver 121 of a wireless communications system 100 will now be described with reference to the flowchart depicted in Fig. 3. Fig. 3 is an illustrated example of actions or operations which may be taken by a transmitter 1 10 in the wireless communication network 100. Action 301

Optionally, the transmitter 1 10 may transmit a request for information indicating the time period needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121. This means, for example, that the transmitter 1 10 may send a dedicated request to the receiver 121 requesting the information indicating the time period needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121.

Action 302

According to another option, the transmitter 1 10 may transmit reference signals in a set of symbols using a set of transmitter beams to the receiver 121 prior to determining the number of symbols to use for the reference signals that is to be transmitted to the receiver 121 using one or more transmitter beams in Action 305.

It should here be noted that receiver beam sweeps and transmitter beam sweeps may be done sequentially, as described with reference to Fig. 5 below, or in an interleaved/joint manner, as described with reference to Fig. 6 below. However, with the sequential approach, the transmitter beam sweep step is commonly referred to as the P2 step, while the receive beam sweep is commonly referred to as the P3 step. Therefore, it should also be noted that transmitting the set of transmitter beams may here be performed as part of a transmitter or transmit beam sweep commonly referred to as the P2 step as indicated above. In this P2 step, one or more transmitter or transmit beams may be swept, i.e. tested or sounded, sequentially.

Action 303

According to another option, the transmitter 1 10 may transmit a beam sweeping pattern of the one or more transmitter beams to the receiver 121. This means, for example, that the transmitter 110 may transmit information indication a time or symbols duration for which the transmitter 110 will keep the transmitter beam constant, thus allowing the receiver 121 to sweep multiple receiver beams, e.g. in a single OFDM symbol if this is indicated by the transmitter beam sweeping pattern.

Action 304

In some embodiments, the transmitter 110 may receive information indicating the time period needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121.

According to some embodiments, the transmitter 110 may receive the information indicating the time period via one of: a Physical Uplink Shared Channel, PUSCH; a Physical Uplink Control Channel, PUCCH; Radio Resource Control, RRC, signalling; or via a Control Element, CE, on the Media Access Control, MAC, layer.

Action 305

In this action, the transmitter 1 10 may determine a number of symbols to use for the reference signals that are to be transmitted to the receiver 121 using one or more transmitter beams based on information indicating a time period needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121. It should be noted here that the symbols used for the reference signals are Orthogonal Frequency Division Multiplexing, OFDM, symbols. The symbols may be full or complete OFDM symbols.

In some embodiments, the transmitter 110 may determine the number of reference symbols further based on one or more of: a category of the receiver 121 ; a location of the receiver 121 ; and information determined by the transmitter 110 of the number of receiver beams to be used when performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121. Here, it should be noted that this also means that the transmitter 1 10 may determine the number of reference symbols further based on known or reported properties of the receiver 121 , such as, the number of receiver antennas at the receiver 121 , or the frequency range of operation of the receiver 121 and the transmitter 110. Also, in case the receiver 121 is associated with a Feature Group Indicator, FGI, in the transmitter 110, then this FGI may also be used by the transmitter 110 when determining the number of reference symbols.

According to some embodiments, the information indicating the time period may comprise information indicating one or more of: a time duration required for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121 , a number of symbols needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121 ; a number of receiver beams to be used when performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121 ; a time duration required for each receiver beam when performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121 ; and a periodicity of the reference signals transmitted for performing the

measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121. Action 306

After the determination in Action 305, the transmitter 110 may transmit the reference signal in the determined number of symbols using the one or more transmitter beams. Example of embodiments of a method performed by a receiver 121 in a wireless communications system 100 for enabling measurements based on reference signals in one or more receiver beams will now be described with reference to the flowchart depicted in Fig. 4. Fig.4 is an illustrated example of actions or operations which may be taken by a receiver 121 in the wireless communication network 100.

Action 401

Optionally, the receiver 121 may receive a request for information indicating the time period needed for performing the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver 121 , whereby the information indicating the time period is transmitted in response to the request. This means, for example, that the receiver 121 may transmit the information indicating the determined time period in Action 406 in response to the received request.

Action 402

According to another option, the receiver 121 may receive a beam sweeping pattern of the one or more transmitter beams to the receiver 121 , whereby the

measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver 121 are performed according to the received beam sweeping pattern. This means, for example, that the receiver 121 may perform the measurements on one or more receiver beams according to the received beam sweeping pattern. The received beam sweeping pattern may also be referred to as a transmit beam sweeping pattern.

Action 403

According to a further option, the receiver 121 may perform measurements on reference signals transmitted from the transmitter 110 in a set of symbols using a set of transmitter beams.

Action 404

After the optional measurements in Action 403, the receiver 121 may determine requested reference signal information based on the performed measurements, whereby the time period needed for performing the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver 121 is determined based on the determined requested reference signal information. This means that the time period needed for performing the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver 121 is determined in Action 405 may be based on the determined requested reference signal information. In some embodiments, the determination of the requested reference signal information may also be referred to as computing requested CSI-RS parameters or calculating requested reference symbol information.

In some embodiments, the receiver 121 may determine the requested reference symbol information further based on a number of receiver beams to be used when performing the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver 121. It is clear that if all other parameters are constant, then the required time for receiver beam sweeping will increase if more receiver beams are to be tested. The number of tested receiver beams in a receiver 121 will most likely, if at all, be varying slowly and may also be part of the UE capability. Additionally, or alternatively, the receiver 121 may determine the requested reference symbol information further based on a beamforming architecture of the receiver 5 121. This may, for example, be a number of concurrent receiver beams capable of being used when performing the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver 121. Basically, this means that, if several receiver beams are evaluated simultaneously, then the required time for receiver beam sweeping would decrease. Similarly, if the beamforming

0 architecture supports testing of both wide and narrow receiver beams, then hierarchical testing may be used. This will further reduce the required receiver beam sweep time. The beamforming architecture of the receiver 121 will most likely, if at all, be varying slowly and may also be part of the UE capability. Additionally, or alternatively, the receiver 121 may determine the requested reference symbol information further based on one or more5 channel states, for example, a path-loss information, a delay spread information, a

Doppler information, and/or previously reported Channel State Information, CSI, information. Here, it should be noted that with higher path loss, more time is required to accumulate enough energy for an accurate measurement of the receiver beams and may thus be taken into account. Additionally, or alternatively, the receiver 121 may determine0 the requested reference symbol information further based on one or more types of measurements requested by the transmitter 110, for example, CQI report information, or a RSRP information. CQI reports require a more high resolution channel estimate and hence would require more time per receiver beam tested, and may thus also be taken into account. Additionally, or alternatively, the receiver 121 may determine the requested5 reference symbol information further based on one or more Quality-of-Service, QoS, requirements, for example, a reliability requirement, a latency requirement, a throughput requirement, a availability requirement, a robustness requirement, and/or a resilience requirement. Here, for example, if latency increases, then the beam sweeping time will also increase and may thus also be taken into account. By considering QoS requirements,0 the reliability of the measurement will increase. Additionally, or alternatively, the receiver 121 may determine the requested reference symbol information further based on receiver mobility information. Similar to latency, there is no point in having long receiver beam sweeps if the mobility of the wireless device 121 makes the best receiver beam change fast. Additionally, or alternatively, the receiver 121 may determine the requested reference5 symbol information further based on received SNR or SINR information. A high SNR may require less time for the receiver beam sweep, and may thus also be taken into account. Additionally, or alternatively, the receiver 121 may determine the requested reference symbol information further based on previously determined reference symbols

information. This may, for example, be used to infer SNR information, etc. Additionally, or alternatively, the receiver 121 may determine the requested reference symbol information further based on one or more qualities, i.e. quantified values or properties of the hardware quality, of hardware components in the receiver 121 , such as, for example, oscillators and amplifiers. This may be advantageous since a higher quality receiver might be able to measure faster, and may be able to switch within an OFDM symbol. Additionally, or alternatively, the receiver 121 may determine the requested reference symbol information further based on one or more of: a state of charge of the battery of the receiver 121 , i.e. energy budget; one or more capabilities of the receiver 121 , for example, used algorithms and/or processing power; and a desired beam switching latency. Action 405

The receiver 121 may determine information indicating a time period needed for performing measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver 121. It should be noted that the information indicating a time period may, according to some embodiments, comprise information indicating one or more of: a time duration required for performing the one or more receiver beam measurements at the receiver 121 ; a number of reference symbols needed for performing the one or more receiver beam measurements at the receiver 121 ; a number of receiver beams to be measured at the receiver 121 ;a time duration required for each receiver beam to be measured at the receiver 121 ; and a periodicity of the determined reference symbols transmitted for performing the one or more receiver beam measurements at the receiver 121.

Action 406

After the determination in Action 405, the receiver 121 may transmit information indicating the time period, for example, to a transmitter 110 in the wireless

communications system 100. According to some embodiments, the receiver 121 may transmit the information indicating the time period is via: a Physical Uplink Shared Channel, PUSCH; a Physical Uplink Control Channel, PUCCH; Radio Resource Control, RRC, signalling; or via a Control Element, CE, on the Media Access Control, MAC, layer. In some embodiments, the information indicating the time period may comprise information indicating one or more of: a time duration required for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121 ; a number of symbols needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121 ; a number of receiver beams to be used when performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121 ; a time duration required for each receiver beam when performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121 ; and a periodicity of the reference signals transmitted for performing the

measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121. Action 407

After the transmission in Action 406, the receiver 121 may perform measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver 121. Fig. 5 shows a signalling scheme of example signalling between a transmitter 110 and in a receiver 121 according to some embodiments. In this example, the receiver beam sweep and transmitter beam sweep are performed sequentially and referred to as P2 and P3, respectively. The transmitter beam sweep is shown in the dashed area denoted P2 in Fig. 5, and the receiver beam sweep is shown in the dashed area denoted P3 in Fig. 5. Fig. 5 is an illustrated example of actions or operations which may be taken by a transmitter 1 10 and the receiver 121 in the wireless communication network 100.

Action 501. The transmitter 110 sweeps, i.e. tests or sounds, one or more transmitter beams sequentially. In other words, the transmitter 1 10 performs a transmit, TX, beam sweep.

Action 502. The receiver 121 measures on each of the one or more transmitter beams. In other words, the transmitter 1 10 performs measurements on TX beams.

Action 503. The receiver 121 calculates/computes the requested CSI-RS parameters. In other words, the transmitter 110 determines requested CSI-RS

information. Action 504. The receiver 121 signals information indicating a measurement time for receive, RX, beam sweep, i.e. the receiver 121 transmit information to the transmitter 1 10 indicating the time it needs for the RX beam sweep. Here, the transmitter 110 receives the signalled information.

Action 505. The transmitter 110 then determines the number of CSI-RS symbols needed for the RX beam sweep, i.e. determine how many CSI-RS symbols are needed for the P3 step.

Action 506. The transmitter 110 then transmits the determined number of CSI-RS symbols using one or more TX-beams, i.e. transmits the determined number of CSI-RS symbols in the P3 step.

Action 507. The receiver 121 then performs measurements on the RX beams.

Fig. 6 shows another signalling scheme of example signalling between a transmitter 1 10 and in a receiver 121 according to some embodiments. In this example, the receiver beam sweeps and transmitter beam sweeps are performed in an

interleaved/joint manner. The joint transmitter beam sweep and the receiver beam sweep is shown in the dashed area denoted P2/P3 in Fig. 6. Fig. 6 is an illustrated example of actions or operations which may be taken by a transmitter 1 10 and the receiver 121 in the wireless communication network 100.

Action 601. The receiver 121 signals information indicating a measurement time for receive, RX, beam sweep, i.e. the receiver 121 transmit information to the transmitter 1 10 indicating the time it needs for the RX beam sweep. Here, the transmitter 110 receives the signalled information.

Action 602. The transmitter 110 then determines the number of CSI-RS symbols needed for the joint TX/RX beam sweep, i.e. determine how many CSI-RS symbols are needed for the joint P2/P3 step.

Action 603. The transmitter 110 performs the joint TX/RX beam sweep, e.g. the transmitter 1 10 first transmit the determined number of CSI-RS symbols using a first TX beam, then the transmitter transmits the determined number of CSI-RS symbols using a second TX beam, and so on and so forth. Here, it should be noted that here the TX beam is kept constant for a number of CSI-RS symbols that is determined based on information indicating the time needed for RX beam sweep.

Action 604. The receiver 121 performs measurements on the RX beams in the joint TX/RX beam sweep. In other words, the RX beams are swept for multiple TX beams. To perform the method actions described herein a transmitter 1 10 and a receiver 121 are provided. Figs. 7-8 are block diagrams depicting embodiments of the wireless transmitter 1 10 and the receiver 121. The transmitter 1 10 is configured to perform the methods described for a transmitter 1 10 according to embodiments herein. The receiver 5 121 is configured to perform the methods described for a receiver 121 according to embodiments herein.

Embodiments herein for enabling measurements based on reference signals in one or more receiver beams at a receiver 121 of a wireless communications network 100 may be implemented through one or more processors 710, i.e. processing circuitry, in0 the transmitter 110 depicted in Fig. 7, together with computer program code for

performing the functions and/or method actions of the embodiments herein. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing embodiments herein when being loaded into the transmitter 110. One such carrier may be in the form of5 a CD ROM disc. It is however feasible with other data carriers such as a memory stick. The computer program code may furthermore be provided as pure program code on a server and downloaded to the transmitter 110.

The transmitter 1 10 may comprise a receiving module 711 and a transmitting module 712 over which the transmitter 110 may transmit/receive signals to other nodes,0 such as, e.g. the receiver 121 or other transmitters/receivers in the wireless

communications network 100. The receiving and transmitting modules 711 , 712 may also be incorporated into a single transceiver or communications unit. Also, the transmitter 110 may comprise an determining module 713 configured to, for example, determine a number of symbols to use for the reference signals that are to be transmitted to the5 receiver 121 using one or more transmitter beams based on information indicating a time period needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121.The transmitter 1 10 further comprises a memory 720. The memory 720 may, for example, be used to store applications or programs to perform the methods herein and/or any

0 information used by such applications or programs. In some embodiments, the transmitter 1 10 may further comprise an input/output interface (not shown), which may be used to communicate over a wired connection with radio network entities or nodes (not shown) in the wireless communications network 100.

In some embodiments, the transmitter 1 10 or the one or more processor 710 may5 be configured to, or comprise a receiving module 71 1 configured to, receive information indicating the time period needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121. In some embodiments, the transmitter 110 or the one or more processor

710 may be configured to, or comprise a transmitting module 71 1 configured to, transmit the reference signal in the determined number of symbols using the one or more transmitter beams. In some embodiments, the transmitter 110 or the one or more processor 710 may be configured to, or comprise a transmitting module 71 1 configured to, transmit a request for information indicating the time period needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121. In some embodiments, the transmitter 110 or the one or more processor 710 may be configured to, or comprise a transmitting module

711 configured to, transmit reference signals in a set of symbols using a set of transmitter beams to the receiver 121 prior to determining the number of symbols to use for the reference signals that is to be transmitted to the receiver 121 using one or more transmitter beams. In some embodiments, the transmitter 110 or the one or more processor 710 may be configured to, or comprise a transmitting module 71 1 configured to, transmit a beam sweeping pattern of the one or more transmitter beams to the receiver 121.

In some embodiments, the information indicating the time period comprise information indicating one or more of: a time duration required for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121 ; a number of symbols needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121 ; a number of receiver beams to be used when performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121 ; a time duration required for each receiver beam when performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121 ; and a periodicity of the reference signals transmitted for performing the

measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121. In some embodiments, the transmitter 1 10 or the one or more processor 710 may be configured to, or comprise an determining module 713 configured to, determine the number of symbols further based on one or more of: a category of the receiver; a location of the receiver; and information determined by the transmitter 110 of the number of receiver beams to be used when performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121. Further, in some embodiments, the transmitter 1 10 or the one or more processor 710 may be configured to, or comprise an determining module 713 configured to, determine the number of symbols further based known or reported properties of the receiver 121 , such as, the number of receiver antennas at the receiver 121 , or the frequency range of operation of the receiver 121 and the transmitter 110. Also, in case the receiver 121 is associated with a Feature Group Indicator, FGI, in the transmitter 110, then the transmitter 110 or the one or more processor 710 may be configured to, or comprise an determining module 713 configured to, determine the number of symbols further based on FGI.

In some embodiments, the transmitter 110 may be, or may be comprised in, a radio base station or network node in the wireless communications network 100, and the receiver 121 may be a mobile terminal or wireless device. Embodiments herein for enabling measurements based on reference signals in one or more receiver beams at a receiver 121 in a wireless communications network 100 may be implemented through one or more processors 810, i.e. processing circuitry, in the receiver 121 depicted in Fig. 8, together with computer program code for performing the functions and/or method actions of the embodiments herein. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing embodiments herein when being loaded into the receiver 121. One such carrier may be in the form of a CD ROM disc. It is however feasible with other data carriers such as a memory stick. The computer program code may furthermore be provided as pure program code on a server and downloaded to the receiver 121.

The receiver 121 comprises a receiving module 811 and a transmitting module 812 over which the receiver 121 may transmit/receive signals to other nodes, such as, e.g. the transmitter 1 10 or other transmitters/receivers in the wireless communications network 100. The receiving and transmitting modules 81 1 , 812 may also be incorporated into a single transceiver or communications unit. Also, the receiver 121 may comprise a determining module 813 configured to, for example, determine information indicating a time period needed for performing measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver 121. The receiver 121 or the one or more processor 810 may be configured to, or comprise a transmitting module 812 configured to, transmit the determined information indicating a time period, e.g. to a transmitter 110 in the wireless communications network 100.

Further, the receiver 121 may comprise a performing module 814 configured to, for example, perform measurements on reference signals transmitted from the transmitter 1 10 in a set of symbols using a set of transmitter beams. In this case, the determining module 813 may also be configured to, for example, determine requested reference signal information based on the performed measurements, whereby the time period needed for performing the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver 121 is determined based on the determined requested reference signal information. The performing module 814 may also be configured to perform measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver 121. The receiver 121 further comprises a memory 820. The memory 820 may, for example, be used to store applications or programs to perform the methods herein and/or any information used by such applications or programs.

In some embodiments, the receiver 121 or the one or more processor 810 may be configured to, or comprise an performing module 814 configured to, perform

measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver 121. In some embodiments, the receiver 121 or the one or more processor 810 may be configured to, or comprise an performing module 814 configured to, perform measurements on reference signals transmitted from the transmitter 110 in a set of symbols using a set of transmitter beams, and determine requested reference signal information based on the performed measurements, whereby the time period needed for performing the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver 121 is determined based on the determined requested reference signal information. In some embodiments, the requested reference signal information may be on one or more of: a number of receiver beams to be used when performing the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver 121 ; a beamforming architecture of the receiver 121 ; one or more channel states; one or more types of measurements requested by the transmitter 110; one or more capabilities of the receiver 121 ; one or more Quality-of-Service, QoS, requirements; receiver mobility information; a state of charge of the battery of the receiver 121 ; received SNR or SINR information; previously determined reference symbols information; a desired beam switching latency; and one or more quality of hardware components in the receiver 121.

In some embodiments, the information indicating the time period comprise information indicating one or more of: a time duration required for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121 ; a number of symbols needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121 ; a number of receiver beams to be used when performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121 ; a time duration required for each receiver beam when performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121 ; and a periodicity of the reference signals transmitted for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver 121.

In some embodiments, the receiver 121 or the one or more processor 810 may be configured to, or comprise a receiving module 811 configured to, receive a request for information indicating the time period needed for performing the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver 121 , whereby the information indicating the time period is transmitted in response to the request. In some embodiments, the receiver 121 or the one or more processor 810 may be configured to, or comprise a receiving module 811 configured to, receive a beam sweeping pattern of the one or more transmitter beams to the receiver 121 , whereby the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver 121 are performed according to the received beam sweeping pattern.

As will be readily understood by those familiar with communications design, that functions from other circuits may be implemented using digital logic and/or one or more microcontrollers, microprocessors, or other digital hardware. In some embodiments, several or all of the various functions may be implemented together, such as in a single application-specific integrated circuit (ASIC), or in two or more separate devices with appropriate hardware and/or software interfaces between them. Several of the functions may be implemented on a processor shared with other functional

components of a wireless device or network node. Alternatively, several of the functional elements of processing circuits discussed may be provided through the use of dedicated hardware, while others are provided with hardware for executing software, in association with the appropriate software or firmware. Thus, the term "processor" or "controller" as may be used herein does not exclusively refer to hardware capable of executing software and may implicitly include, without limitation, digital signal processor (DSP) hardware, read-only memory (ROM) for storing software, random-access memory for storing software and/or program or application data, and non-volatile memory. Other hardware, conventional and/or custom, may also be included.

Designers of transmitters and receivers will appreciate the cost, performance, and maintenance trade-offs inherent in these design choices. The different actions taken by the different nodes may be implemented with different circuits.

From the above it may be seen that the embodiments may further comprise a computer program product, comprising instructions which, when executed on at least one processor, e.g. the processors 710, 810, cause the at least one processor to carry out the method for enabling measurements based on reference signals in one or more receiver beams at a receiver 121 in the wireless communications network 100. Also, some embodiments may, as described above, further comprise a carrier containing said computer program, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

Additional details of the receiver 121 , referred to as user equipment or wireless device 121 below, are shown in relation to Fig. 9. As shown in Fig. 9, the example user equipment 121 includes an antenna 940, radio circuitry (e.g. radio front-end circuitry) 910, processing circuitry 920, and the user equipment 121 may also include a memory 930. The memory 930 may be separate from the processing circuitry 920 or an integral part of processing circuitry 920. Antenna 940 may include one or more antennas or antenna arrays and is configured to send and/or receive wireless signals, and is connected to radio circuitry (e.g. radio front-end circuitry) 910. In certain alternative embodiments, user equipment 121 may not include antenna 940, and antenna 940 may instead be separate from user equipment 121 and be connectable to user equipment 121 through an interface or port.

The radio circuitry (e.g. radio front-end circuitry) 910 may comprise various filters and amplifiers, is connected to antenna 940 and processing circuitry 920, and is configured to condition signals communicated between antenna 940 and processing circuitry 920. In certain alternative embodiments, user equipment 121 may not include radio circuitry (e.g. radio front-end circuitry) 910, and processing circuitry 920 may instead be connected to antenna 940 without front-end circuitry 910.

Processing circuitry 920 may include one or more of radio frequency (RF) transceiver circuitry, baseband processing circuitry, and application processing circuitry. In some embodiments, the RF transceiver circuitry 921 , baseband processing circuitry 922, and application processing circuitry 923 may be on separate chipsets. In alternative embodiments, part or all of the baseband processing circuitry 922 and application processing circuitry 923 may be combined into one chipset, and the RF transceiver circuitry 921 may be on a separate chipset. In still alternative embodiments, part or all of the RF transceiver circuitry 921 and baseband processing circuitry 922 may be on the same chipset, and the application processing circuitry 923 may be on a separate chipset. In yet other alternative embodiments, part or all of the RF transceiver circuitry 921 , baseband processing circuitry 922, and application processing circuitry 923 may be combined in the same chipset. Processing circuitry 920 may include, for example, one or more central processing units (CPUs), one or more microprocessors, one or more application specific integrated circuits (ASICs), and/or one or more field programmable gate arrays (FPGAs).

The user equipment 121 may include a power source 950. The power source 950 may be a battery or other power supply circuitry, as well as power management circuitry. The power supply circuitry may receive power from an external source. A battery, other power supply circuitry, and/or power management circuitry are connected to radio circuitry (e.g. radio front-end circuitry) 910, processing circuitry 920, and/or memory 930. The power source 950, battery, power supply circuitry, and/or power management circuitry are configured to supply user equipment 121 , including processing circuitry 920, with power for performing the functionality described herein.

Additional details of the transmitter 1 10, referred to as radio base station 110 below, are shown in relation to Fig. 10. As shown in Fig. 10, the example radio network node 110 includes an antenna 1040, radio circuitry (e.g. radio front-end circuitry) 1010, processing circuitry 1020, and the radio network node 110 may also include a memory 1030. The memory 1030 may be separate from the processing circuitry 1020 or an integral part of processing circuitry 1020. Antenna 1040 may include one or more antennas or antenna arrays and is configured to send and/or receive wireless signals, and is connected to radio circuitry (e.g. radio front-end circuitry) 1010. In certain alternative embodiments, radio network node 110 may not include antenna 1040, and antenna 1040 may instead be separate from radio network node 110 and be connectable to radio network node 110 through an interface or port.

The radio circuitry (e.g. radio front-end circuitry) 1010 may comprise various filters and amplifiers, is connected to antenna 1040 and processing circuitry 1020, and is 5 configured to condition signals communicated between antenna 1040 and processing circuitry 1020. In certain alternative embodiments, radio network node 110 may not include radio circuitry (e.g. radio front-end circuitry) 1010, and processing circuitry 1020 may instead be connected to antenna 1040 without front-end circuitry 1010.

Processing circuitry 1020 may include one or more of radio frequency (RF)

10 transceiver circuitry, baseband processing circuitry, and application processing circuitry.

In some embodiments, the RF transceiver circuitry 1021 , baseband processing circuitry 1022, and application processing circuitry 1023 may be on separate chipsets. In alternative embodiments, part or all of the baseband processing circuitry 1022 and application processing circuitry 1023 may be combined into one chipset, and the RF

15 transceiver circuitry 1021 may be on a separate chipset. In still alternative embodiments, part or all of the RF transceiver circuitry 1021 and baseband processing circuitry 1022 may be on the same chipset, and the application processing circuitry 1023 may be on a separate chipset. In yet other alternative embodiments, part or all of the RF transceiver circuitry 1021 , baseband processing circuitry 1022, and application processing circuitry

20 1023 may be combined in the same chipset. Processing circuitry 1020 may include, for example, one or more central processing units (CPUs), one or more microprocessors, one or more application specific integrated circuits (ASICs), and/or one or more field programmable gate arrays (FPGAs).

The radio network node 110 may include a power source 1050. The power source

25 1050 may be a battery or other power supply circuitry, as well as power management circuitry. The power supply circuitry may receive power from an external source. A battery, other power supply circuitry, and/or power management circuitry are connected to radio circuitry (e.g. radio front-end circuitry) 1010, processing circuitry 1020, and/or memory 1030. The power source 1050, battery, power supply circuitry, and/or power

30 management circuitry are configured to supply radio network node 110, including

processing circuitry 1020, with power for performing the functionality described herein.

Additional aspects

Further objects of the embodiments herein may be to improve measurements 35 based on reference signals in one or more receiver beams at a receiver in a wireless communications network, and/or reduce signalling overhead in a wireless communications network.

According to a first additional aspect of embodiments herein, a method performed in a transmitter for enabling measurements based on reference signals in one or more receiver beams at a receiver of a wireless communications network is provided. The transmitter may determine a number of symbols to use for the reference signals that is to be transmitted to the receiver using one or more transmitter beams based on information indicating a time period needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver. In some embodiments, the transmitter may receive information indicating the time period needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver. In some

embodiments, the transmitter may transmit reference signals in the determined number of reference symbols using one or more transmitter beams. Also, in some embodiments, the transmitter may transmit a request for information indicating the time period needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver. The transmitter may also, in some embodiments, transmit reference signals in a set of reference symbols using a set of transmitter beams to the receiver prior to determining the number of symbols to use for the reference signals that is to be transmitted to the receiver using one or more transmitter beams. The transmitter may further, in some embodiments, transmit a beam sweeping pattern of the one or more transmitter beams to the receiver. The beam sweeping pattern may also be referred to as a transmit beam sweeping pattern. In some embodiments, the information indicating the time period may comprise information indicating one or more of: a time duration required for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver; a number of symbols needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver; a number of receiver beams to be used when performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver; a time duration required for each receiver beam when performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver; and a periodicity of the reference signals transmitted for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver. Also, in some embodiments, the information indicating the time period may be received via: a Physical Uplink Shared Channel, PUSCH; a Physical Uplink Control Channel, PUCCH; Radio Resource Control, RRC, signalling; or via a Control Element, CE, on the Media Access Control, MAC, layer. According to some embodiments, the transmitter may determine the number of reference symbols is further based on one or more of: a category of the receiver (or wireless device in which it may be comprised); a location of the receiver; and information determined by the transmitter of the number of receiver beams to be used when performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver.

Furthermore, according to some embodiments, the transmitter may be, or may be comprised in, a radio base station or network node in the wireless communications network. Also, in some embodiments, the receiver may be, or may be comprised in, a mobile terminal or wireless device. In some embodiments, the symbols used for the reference signals are Orthogonal Frequency Division Multiplexing, OFDM, symbols.

According to a second additional aspect of embodiments herein, a transmitter configured to perform the method described above is also provided.

According to a third additional aspect of embodiments herein, a method performed by a receiver for enabling measurements based on reference signals in one or more receiver beams in a wireless communications network is provided. The receiver may determine information indicating a time period needed for performing measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver. Also, the transmitter may transmit information indicating the time period to a transmitter in the wireless communications network. In some embodiments, the receiver may perform measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver. The receiver may also, in some embodiments, perform measurements on reference signals transmitted from the transmitter in a set of symbols using a set of transmitter beams. In this case, the receiver may further determine requested reference signal information based on the performed measurements, whereby the time period needed for performing the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver is determined based on the determined requested reference signal information. In some embodiments, the requested reference symbol information may further be based on one or more of: a number of receiver beams to be used when performing the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver; a beamforming architecture of the receiver, for example, a number of concurrent receiver beams capable of being used when performing the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver; one or more channel states, for example, a path-loss information, a delay spread information, a Doppler information, and/or previously reported Channel State Information, CSI, information; one or more types of measurements requested by the transmitter, for example, CQI report information, or a RSRP information; one or more capabilities of the receiver, for example, used algorithms and/or processing power; one or more Quality-of- Service, QoS, requirements, for example, a reliability requirement, a latency

requirement, a throughput requirement, a availability requirement, a robustness requirement, and/or a resilience requirement; receiver mobility information; a state of charge of the battery of the receiver, i.e. energy budget; received SNR or SINR information; previously determined reference symbols information; a desired beam switching latency; and one or more quality of hardware components in the receiver, for example, the quality or properties of oscillators and amplifiers in the receiver. In some embodiments, the information indicating the time period may comprise information indicating one or more of: a time duration required for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver; a number of symbols needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver; a number of receiver beams to be used when performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver; a time duration required for each receiver beam when performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver; and a periodicity of the reference signals transmitted for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver. According to some embodiments, the information indicating the time period may be transmitted by the receiver via: a Physical Uplink Shared Channel, PUSCH; a Physical Uplink Control Channel, PUCCH; Radio Resource Control, RRC, signalling; or via a Control Element, CE, on the Media Access Control, MAC, layer. In some embodiments, the receiver may receive a request for information indicating the time period needed for performing the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver, whereby the information indicating the determined time period is transmitted in response to the request. In some embodiments, the receiver may receive a beam sweeping pattern of the one or more transmitter beams to the receiver, whereby the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver are performed according to the received beam sweeping pattern. The beam sweeping pattern may also be referred to as a transmit beam sweeping pattern.

Furthermore, according to some embodiments, the transmitter may be, or may be comprised in, a radio base station or network node in the wireless communications network. Also, in some embodiments, the receiver may be, or may be comprised in, a mobile terminal or wireless device.

According to a fourth additional aspect of embodiments herein, a receiver configured to perform the method described above is also provided.

The terminology used in the detailed description of the particular embodiments illustrated in the accompanying drawings is not intended to be limiting of the described transmitter, receiver or methods therein.

As used herein, the term "and/or" comprises any and all combinations of one or more of the associated listed items. Further, as used herein, the common abbreviation "e.g.", which derives from the Latin phrase "exempli gratia," may be used to introduce or specify a general example or examples of a previously mentioned item, and is not intended to be limiting of such item. If used herein, the common abbreviation "i.e.", which derives from the Latin phrase "id est," may be used to specify a particular item from a more general recitation. The common abbreviation "etc.", which derives from the Latin expression "et cetera" meaning "and other things" or "and so on" may have been used herein to indicate that further features, similar to the ones that have just been

enumerated, exist.

As used herein, the singular forms "a", "an" and "the" are intended to comprise also the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms "includes," "comprises," "including" and/or "comprising," when used in this specification, specify the presence of stated features, actions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, actions, integers, steps, operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms comprising technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the described embodiments belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The embodiments herein are not limited to the above described preferred embodiments. Various alternatives, modifications and equivalents may be used.

Therefore, the above embodiments should not be construed as limiting.

Abbreviations

PUSCH Physical Uplink Shared Channel

PUCCH Physical Uplink Control Channel

RRC Radio Resource Control

CE Control Element

MAC Media Access Control

IFDMA Interleaved Frequency-Division Multiple Access

TTU Transmission Time Unit

CSI-RS Channel State-Information Reference Symbols

RSPR Reference Signal Received Power

OFDM Orthogonal Frequency Division Multiplexing

CQI Channel Quality Indicator

QoS Quality-of-Service

SNR Signal-to-Noise Ratio

SINR Signal-to-lnterference plus Noise Ratio

Claims

1. A method performed in a transmitter (1 10) for enabling measurements based on reference signals in one or more receiver beams at a receiver (121) in a wireless communications system (100), the method comprising

determining (305, 505, 602) a number of symbols to use for the reference signals that are to be transmitted to the receiver (121) using one or more transmitter beams based on information indicating a time period needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver (121).

2. The method according to claim 1 , further comprising

receiving (304, 504, 601) information indicating the time period needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver (121).

3. The method according to claim 1 or 2, further comprising

transmitting (306, 506, 603) the reference signal in the determined number of symbols using the one or more transmitter beams.

4. The method according to any of claims 1-3, further comprising

transmitting (301) a request for information indicating the time period needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver (121).

5. The method according to any of claims 1-4, further comprising

transmitting (302, 501) reference signals in a set of symbols using a set of transmitter beams to the receiver (121) prior to determining the number of symbols to use for the reference signals that is to be transmitted to the receiver (121) using one or more transmitter beams.

6. The method according to any of claims 1-5, further comprising

transmitting (303) a beam sweeping pattern of the one or more transmitter beams to the receiver (121).

The method according to any of claims 1-6, wherein the information indicating the time period comprise information indicating one or more of:

a time duration required for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver (121),

a number of symbols needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver (121);

a number of receiver beams to be used when performing the

measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver (121);

a time duration required for each receiver beam when performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver (121); and a periodicity of the reference signals transmitted for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver (121).

The method according to any of claims 1-7, wherein determining the number of symbols is further based on one or more of:

a category of the receiver;

a feature group indicator (FGI) of the receiver;

a location of the receiver;

the number of receiver antennas;

the frequency range of operation; and

information determined by the transmitter (110) of the number of receiver beams to be used when performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver (121).

The method according to any of claims 1-8, wherein the symbols used for the reference signals are Orthogonal Frequency Division Multiplexing, OFDM, symbols.

10. A transmitter (110) for enabling measurements based on reference signals in one or more receiver beams at a receiver (121) in a wireless communications system (100), the transmitter (1 10) being configured to

determine a number of symbols to use for the reference signals that are to be transmitted to the receiver (121) using one or more transmitter beams based on information indicating a time period needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver (121).

1 1. The transmitter (110) according to claim 10, further configured to receive

information indicating the time period needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver (121).

12. The transmitter (110) according to claim 10 or 1 1 , further configured to transmit the reference signal in the determined number of symbols using the one or more transmitter beams.

13. The transmitter (1 10) according to any of claims 10-12, further configured to

transmit a request for information indicating the time period needed for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver (121).

14. The transmitter (1 10) according to any of claims 10-13, further configured to

transmit reference signals in a set of symbols using a set of transmitter beams to the receiver (121) prior to determining the number of symbols to use for the reference signals that is to be transmitted to the receiver (121) using one or more transmitter beams.

15. The transmitter (1 10) according to any of claims 10-15, further configured to

transmit a beam sweeping pattern of the one or more transmitter beams to the receiver (121).

16. The transmitter (1 10) according to any of claims 10-16, wherein the information indicating the time period comprise information indicating one or more of: a time duration required for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver (121),

a number of receiver beams to be used when performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver (121);

17. The transmitter (1 10) according to any of claims 10-16, wherein determining the number of symbols is further based on one or more of:

a category of the receiver;

- a feature group indicator (FGI) of the receiver;

a location of the receiver;

the number of receiver antennas;

the frequency range of operation; and

18. The transmitter (1 10) according to any of claims 10-17, wherein the transmitter (1 10) is, or is comprised in, a radio base station or network node in the wireless communications network (100), and the receiver (121) is a mobile terminal or wireless device.

19. The transmitter (110) comprising at least one processing circuitry (710) and a memory (720), wherein the memory (720) comprise instructions executable by the at least one processing circuitry (710).

20. A method performed by a receiver (121) for enabling measurements based on reference signals from a transmitter (1 10) in the wireless communications system (100) in one or more receiver beams, the method comprising

determining (405) information indicating a time period needed for performing measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver (121); and

transmitting (406, 504, 601) the determined information indicating the time period.

21. The method according to claim 20, further comprising

performing (407, 507, 604) measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver (121).

22. The method according to claim 20 or 21 , further comprising

performing (403, 502) measurements on reference signals transmitted from the transmitter (110) in a set of symbols using a set of transmitter beams;

determining (404, 503) requested reference signal information based on the performed measurements, whereby the time period needed for performing the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver (121) is determined based on the determined requested reference signal information.

23. The method according to any of claims 20-22, wherein the requested reference signal information may be on one or more of:

a number of receiver beams to be used when performing the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver (121); a beamforming architecture of the receiver (121);

one or more channel states;

one or more types of measurements requested by the transmitter (1 10); one or more capabilities of the receiver (121);

one or more Quality-of-Service, QoS, requirements;

receiver mobility information;

a state of charge of the battery of the receiver (121);

- received SNR or SINR information;

previously determined reference symbols information; a desired beam switching latency; and

one or more quality of hardware components in the receiver (121).

24. The method according to any of claims 20-23, wherein the information indicating the time period comprise information indicating one or more of:

a time duration required for performing the measurements based on the reference signals comprised in symbols received in the one or more receiver beams at the receiver (121);

25. The method according to any of claims 20-24, further comprising

receiving (401) a request for information indicating the time period needed for performing the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver (121), whereby the information indicating the time period is transmitted in response to the request.

26. The method according to any of claims 20-25, further comprising receiving (402) a beam sweeping pattern of the one or more transmitter beams to the receiver (121), whereby the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver (121) are performed according to the received beam sweeping pattern.

27. A receiver (121) for enabling measurements based on reference signals from a transmitter (110) in the wireless communications system (100) in one or more receiver beams, the receiver (121) being configured to

determine information indicating a time period needed for performing measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver (121), and transmit information indicating the time period to a transmitter (1 10) in the wireless communications system (100).

28. The receiver (121) according to claim 27, further configured to perform

measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver (121).

29. The receiver (121) according to claim 27 or 28, further configured to perform

measurements on reference signals transmitted from the transmitter (1 10) in a set of symbols using a set of transmitter beams, and determine requested reference signal information based on the performed measurements, whereby the time period needed for performing the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver (121) is determined based on the determined requested reference signal information.

30. The receiver (121) according to any of claims 27-29, wherein the requested

reference signal information may be on one or more of:

one or more channel states;

one or more Quality-of-Service, QoS, requirements;

receiver mobility information;

a state of charge of the battery of the receiver (121);

- received SNR or SINR information;

previously determined reference symbols information;

a desired beam switching latency; and

one or more quality of hardware components in the receiver (121).

31. The receiver (121) according to any of claims 27-30, wherein the information

indicating the time period comprise information indicating one or more of:

32. The receiver (121) according to any of claims 27-31 , further configured to receive a request for information indicating the time period needed for performing the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver (121), whereby the information indicating the time period is transmitted in response to the request.

33. The receiver (121) according to any of claims 27-32, further configured to receive a beam sweeping pattern of the one or more transmitter beams to the receiver (121), whereby the measurements based on the reference signals comprised in symbols received using the one or more receiver beams at the receiver (121) are performed according to the received beam sweeping pattern.

34. The receiver (121) according to any of claims 27-33, wherein the transmitter (1 10) is, or is comprised in, a radio base station or network node in the wireless communications network (100), and the receiver (121) is, or is comprised in, a mobile terminal or wireless device.

35. The receiver (121) comprising at least one processing circuitry (810) and a

memory (820), wherein the memory (820) comprise instructions executable by the at least one processing circuitry (810).

36. A computer program, comprising instructions which, when executed on at least one processor (710, 810), cause the at least one processor (710, 810) to carry out the method according to any of claims 1-9 or 20-26.

37. A carrier containing the computer program according to claim 36, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer- readable storage medium.