WO2025136160A1

WO2025136160A1 - Beam weight selection for communication with a user equipment

Info

Publication number: WO2025136160A1
Application number: PCT/SE2023/051285
Authority: WO
Inventors: Peter Almers; Bo Göransson; Martin Alm; Jing Rao
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2023-12-20
Filing date: 2023-12-20
Publication date: 2025-06-26
Anticipated expiration: 2026-06-20

Abstract

There is provided techniques for beam weight selection for communication with a user equipment. A method is performed by a baseband device. The method comprises receiving, by a receiver in the baseband device, a signal from the user equipment. The signal is received with the receiver operating on one component carrier in an operational bandwidth. The method comprises estimating a direction towards the user equipment from the received signal. The method comprises sending, over an interface and to a radio device, an indication of the direction towards the user equipment.

Description

BEAM WEIGHT SELECTION

FOR COMMUNICATION WITH A USER EQUIPMENT

TECHNICAL FIELD

Embodiments presented herein relate to methods, a baseband device, a radio device, computer programs, and a computer program product for beam weight selection for communication with a user equipment.

BACKGROUND

In general terms, the bandwidth of a mobile communications system grows with the carrier frequency. In other words, higher frequency bands commonly provide larger bandwidths for mobile communications than lower frequency bands. But higher carrier frequencies commonly also yield higher pathloss. In turn, this can cause coverage problems for existing mobile communications systems. In Fig. 1 is schematically illustrated an example communications system 100 where a network node (NN) no and a user equipment (UE) 120 are configured for wireless communication with each other.

One way to address the pathloss issue is to increase the antenna area of the network equipment (such as the antenna area of the network node no and/or the user equipment 120) and introduce beamforming (BF) functionality. By this, the array gain can be used to combat the increased pathloss. The beamforming functionality can be implemented in many ways, such as either fully digital BF (DBF), analog BF (ABF) or a combination of these, also known as hybrid BF (HBF). In Fig. 2 is schematically illustrated an example HBF transmitter implementation of a beamforming network 200. A signal to be transmitted, s(t), is digitally beamformed with weights WD in a DBF module, and a number of (digital) ports are created (three in the figure). Each of these digital ports is further expanded to feed a number of antenna elements in an antenna array by an analog beamformer (ABF) with weights WAX, where x=i, 2, 3. In the receive direction the reciprocal operations are performed. An analog weight is applied over a number of antenna elements to create an analog beam port. The signal from each beam port is digitized and a digital beam weight WD is applied to produce the received signal r(t). In Fig. 2 is further illustrated a rectangular antenna array structure 250 that could be divided into subpanels in many ways. A typical implementation is to divide each column into N parts, where each part is connected to an analog beamformer. Then, digital beamforming can be performed between ports of the same column, but also between ports of different columns. However, it is also possible to create two-dimensional subpanels where each ABF connects to several columns. The most general case is where each subpanel has different sizes as in the illustrated array structure 250.

If a large bandwidth is available, it is common to divide this into several component carriers (CCs) and then use carrier aggregation (CA) when a larger bandwidth is needed. There are several reasons for this. According to one example, the numerology (of the used air interface, such as the new radio (NR) air interface), does not support a very large carrier bandwidth. According to another example, the available spectrum needs be divided between several mobile network operators, etc. In Fig. 3 is schematically illustrated a typical frequency allocation 300 of K component carriers CCi:CCKfor frequency range 2 (FR2).

As a non-limiting example, when implementing wideband BF with phase shifters, beam squint might occur. Since the physical distance between antenna elements is fixed, but the electrical distance measured in wavelength is frequency dependent, a beam pointing error will occur if BF weights designed for one carrier frequency (or CC) is applied to another carrier frequency (or CC). For smaller bandwidths, the beam squint might be negligible but for large bandwidths and large antenna arrays the beam squint may be an issue.

Fully digital baseband beamforming (which could circumvent the beam squint problem) would be extremely complex when scaling the array size and the bandwidth. Assuming an antenna array with 1000 antenna elements and supporting 1 GHz of bandwidth, sampling each antenna element would lead to a very high bitrate on the digital interfaces. It will also lead to a challenging situation in the baseband if beamforming weights for all antenna ports should be calculated on the fly, etc. For lower frequency bands (for example lower than mmWave bands), the beamforming functionality can be implemented in the OFDM frequency domain, that is, before an inverse discrete Fourier transform (IDFT) is performed in the transmitter in the network node 110. By this, it is possible for the network node 110 to multiplex several user equipment 120 with different BF weights in one OFDM symbol. When ABF or HBF is used, the BF takes place on the OFDM time-domain (TD) waveform which means that one BF weight is applied to all frequency resources in one OFDM symbol.

The implementation of the time-domain BF can be either digital or analog, or potentially a combination (i.e., using HBF). The use of TDBF only focusing on relevant time-domain beams will limit the flexibility of the BF implementation, but greatly reduce the burden on the digital interface as well as required processing since the number of ports handed are reduced considerably.

To further simplify the BF implementation, it is common to use a codebook. In general terms, a codebook can be regarded as a table with pre-defined BF weights indexed by a beam index (BI). If maximizing the equivalent isotropic radiated power or sensitivity is important, the codebook can consist of beamforming vectors providing a linear phase front which will maximize the beam gain. One such example is to use BF vectors generated by an DFT (Discrete Fourier Transform). That is, BF vectors where the phase progression is uniformly spread around the unit circle.

Another alternative is to spread the pointing directions of the beams uniformly in space.

One drawback of using TDBF is that received signals have been spatially filtered by the beam when received in baseband. To circumvent this drawback, it is possible to receive a fraction of the bandwidth over all antenna ports. Using the complete bandwidth would require a very wide bandwidth of the interfaces and also drive the complexity of the baseband algorithms, but if, for example, only 1 MHz of the total 1

GHz bandwidth is sampled per antenna, this could save 1000 times on the communication interface. For this, a so-called narrow band receiver (NBR) can be implemented. With an NBR it is possible to get information about the wireless channel in all directions but only for a fraction of the supported bandwidth. Further, a DFT based codebook facilitates using fast Fourier transform (FFT) based algorithms when estimating the best beam from NBR data. For example, the largest peak of an FFT of the covariance of the channel estimates would indicate which beam contain most received power. If a general codebook is used, this best beam could be calculated by searching for the entry of the codebook applied to the channel estimates yielding largest received power. This has much higher complexity than an FFT operation. Furthermore, if the codebook consists of an over-sampled DFT matrix (e.g., the codebook if formed by a DFT twice or four times the number of antenna ports) it would be sufficient to calculate the M-FFT (where M is the number of antenna ports) and then interpolate the codebook.

One issue that occur when codebooks are used in communications systems utilizing large system bandwidths is the beam squint. If the codebook entries are designed to point in a specific direction for a given carrier frequency fl, they will point in a slightly different direction when applied for another given carrier frequency f2. One way to address this issue is to have one codebook per CC, thereby compensating for beam squint. One drawback of this is that the identification of the best beam must be per CC. This will add complexity and will also make use of the NBR difficult. Since the NBR has a very narrow bandwidth compared to the total system bandwidth, it might not be possible to estimate the best beam per CC. Alternatively, one NBR per CC can be implemented, but that would increase implementation complexity. Furthermore, it is common to have a much larger allocation of CCs in the downlink compared to the uplink. As a consequence of this, there might not be an uplink CC to measure on for all CCs used in the downlink.

One issue with using codebooks combined with a NBR is the determination of the correct BF vector that should be applied on a different frequency than the one NBR is operating on. Even if one codebook (compensating for beam squint) is defined per CC, there has to be a mapping between the measurement frequency of the NBR and the BI per CC, which yields in a high implementation complexity.

SUMMARY

An object of embodiments herein is to address the above issues with respect to selection of beam weights.

According to a first aspect there is presented a baseband device for beam weight selection for communication with a user equipment. The baseband device comprises a receiver configured to receive a signal from the user equipment. The signal is received with the receiver operating on one component carrier in an operational bandwidth. The baseband device comprises a direction estimator configured to estimate a direction towards the user equipment from the received signal. The baseband device comprises an interface configured to send, to a radio device, an indication of the direction towards the user equipment. According to a second aspect there is presented a method for beam weight selection for communication with a user equipment. The method is performed by a baseband device. The method comprises receiving, by a receiver in the baseband device, a signal from the user equipment. The signal is received with the receiver operating on one component carrier in an operational bandwidth. The method comprises estimating a direction towards the user equipment from the received signal. The method comprises sending, over an interface and to a radio device, an indication of the direction towards the user equipment.

According to a third aspect there is presented a computer program for beam weight selection for communication with a user equipment. The computer program comprises computer code which, when run on processing circuitry of a baseband device, causes the baseband device to perform actions. One action comprises the baseband device to receive, by a receiver in the baseband device, a signal from the user equipment. The signal is received with the receiver operating on one component carrier in an operational bandwidth. One action comprises the baseband device to estimate a direction towards the user equipment from the received signal. One action comprises the baseband device to send, over an interface and to a radio device, an indication of the direction towards the user equipment.

According to a fourth aspect there is presented a radio device for beam weight selection for communication with a user equipment. The radio device comprises an interface configured to receive, from a baseband device, an indication of a direction towards the user equipment. The radio device comprises a beam weight selector configured to select beam weights from a beamforming codebook. The beam weights are selected that, out of all beam weights in the beamforming codebook, yield a directional beam that is closest to the direction for at least one component carrier.

The radio device comprises a beamforming network configured to apply the beam weights during communication with the user equipment.

According to a fifth aspect there is presented a method for beam weight selection for communication with a user equipment. The method is performed by a radio device. The method comprises receiving, from a baseband device and over an interface, an indication of a direction towards the user equipment. The method comprises selecting beam weights from a beamforming codebook. The beam weights are selected that, out of all beam weights in the beamforming codebook, yield a directional beam that is closest to the direction for at least one component carrier. The method comprises applying, by a beamforming network in the radio device, the beam weights during communication with the user equipment. According to a sixth aspect there is presented a computer program for beam weight selection for communication with a user equipment. The computer program comprises computer code which, when run on processing circuitry of a radio device, causes the radio device to perform actions. One action comprises the radio device to receive, from a baseband device and over an interface, an indication of a direction towards the user equipment. One action comprises the radio device to select beam weights from a beamforming codebook. The beam weights are selected that, out of all beam weights in the beamforming codebook, yield a directional beam that is closest to the direction for at least one component carrier. One action comprises the radio device to apply, by a beamforming network in the radio device, the beam weights during communication with the user equipment.

According to a seventh aspect there is presented a computer program product comprising a computer program according to at least one of the third aspect and the sixth 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, by the signal received from the user equipment only occupying one component carrier, this provides a low load on the air interface.

Advantageously, these aspects enable beam weights for one or more (dominant) direction towards a user equipment for all component carriers to be determined from a signal received on only one component carrier.

Advantageously, these aspects enable the beam weights to be determined with low complexity both computationally for the direction estimation as well as the load on interfaces between the baseband device and the radio device. Advantageously, these aspects enable the baseband device to use the most computational efficient method to find the direction, without considering the implementation in the radio device.

Advantageously, these aspects can be used to handle beam squint. This is at least partly due to the decoupling between the baseband device and the radio device, since the (dominant) directions are assumed to be agnostic to the component carrier frequencies.

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 is a schematic diagram illustrating a communications system according to embodiments;

Fig. 2 is a schematic illustration of a beamforming network and an antenna array according to an embodiment;

Fig. 3 is a schematic illustration of frequency allocation of component carriers according to an embodiment;

Fig. 4 is a block diagram of a network node according to an embodiment;

Fig. 5 is a block diagram of a baseband device according to an embodiment; Fig. 6 is a block diagram of a radio device according to an embodiment;

Figs. 7 and 8 are flowcharts of methods according to embodiments;

Fig. 9 is a schematic diagram showing structural units of a baseband device according to an embodiment; Fig. io is a schematic diagram showing structural units of a radio device according to an embodiment; and

Fig. n 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.

Some (radio) access network architectures define network nodes (or gNBs) comprising multiple component parts or nodes: a central unit (CU), one or more distributed units (DUs), and one or more radio units (RUs). The protocol layer stack of the network node is divided between the CU, the DUs and the RUs, with one or more lower layers of the stack implemented in the RUs, and one or more higher layers of the stack implemented in the CU and/or DUs. The CU is coupled to the DUs via a fronthaul higher layer split (HLS) network; the CU/DUs are connected to the RUs via a fronthaul lower-layer split (LLS) network. The DU may be combined with the CU in some embodiments, where a combined DU/CU may be referred to as a CU or simply a baseband device, or a radio equipment controller (REC). The RUs are also referred to as radio devices and radio equipment (RE). A communication link for communication of user data messages or packets between the RU and the baseband unit, CU, or DU is referred to as a fronthaul network or interface. Messages or packets may be transmitted from the network node in the downlink (i.e., from the CU to the RU) or received by the network node in the uplink (i.e., from the RU to the CU). Assume a network node no with an antenna array 250 comprising 500 or more antenna elements and supporting a large system bandwidth consisting of several component carriers as indicated in Fig. 3. Further, assume that one codebook is used per CC, or group of CCs, without impacting performance too much. For example, if the same codebook is used for, say, two to four, CCs, the impact from beam squint will be minimal at least for CCs with smaller relative bandwidths.

In Fig. 4 is schematically illustrated a network node (NN) 400 for beam weight selection for communication with a user equipment 120, where the network node 400 comprises a baseband device 410 and a radio device 420. The baseband device 410 and the radio device 420 are configured to communicate with each other over an interface 430. There could be different such interfaces 430. In some examples the interface 430 supports the common public radio interface (CPRI) protocol, and/or the evolved Common Public Radio Interface (eCPRI) protocol, and/or an open radio access network (ORAN) protocol (such as for a lower-layer split (LLS)). In some nonlimiting examples the network node 400 is a (radio) access network node, radio base station, base transceiver station, node B (NB), evolved node B (eNB), gNB, access point, access node, integrated access and backhaul (IAB) node, transmission and reception point (TRP), etc.

At least some of the herein disclosed embodiments are based on estimating a direction (0,<p) to and/or from the network node no, 400 to a user equipment no (in elevation and azimuth), instead of the beam index (BI) for the codebook defined at the operating frequency fo of the receiver in the network node no, 400. An indication of this direction is then sent to the radio device 420. In the radio device 410, the indicated direction can be compared to directions of beams in a codebook and the beam closest to the indicated direction can be selected. The codebook can have different sections with beam weights for different CCs to compensate for beam squint. By this the beam per CC will point towards the indicated direction towards the user equipment no regardless of the carrier frequency and the carrier frequency used when transmitting/receiving a signal for this user equipment 120.

Aspects of the baseband device 410 will be disclosed next with reference to the baseband device (BBD) 500 in the block diagram of Fig. 5.

The baseband device 500 comprises a receiver 510. The receiver 510 is configured to receive a signal from the user equipment 120. The signal might be a reference signal, such as an uplink reference signal, demodulation reference signal, etc., an uplink control signal, or an uplink data signal. The signal is received with the receiver 510 operating on one component carrier CCk in an operational bandwidth. There could be different types of receivers 510. In some embodiments the receiver 510 is an NBR that is only capable of operating on one CC at the time. In some examples, the receiver 510 is configured to have access to all antennas at which the signal is wirelessly received, but only within the operational bandwidth. This case is referred to as full digital beamforming. In cases where analog beamforming is implemented, the receiver 510 might only have access to the ports created by the analog beamformers. Another conceivable configuration is hybrid beamforming, where digital beamforming is applied to signals that have been aggregated in an analog beamforming stage in the receiver 510.

The baseband device 500 comprises a direction estimator 520. The direction estimator 520 is configured to estimate at least one direction towards the user equipment 120 from the received signal. The at least one direction might be expressed in the elevation domain and/or the azimuth domain. In general terms, the direction might be different with respect to what estimation criterion is used by the direction estimator 520. In some embodiments, the direction estimator 520 is configured to estimate the dominant direction towards the user equipment 120. In some embodiments, the direction estimator 520 is configured to estimate two or more directions towards the user equipment 120 (such as the direction of a line-of- sight path to the user equipment 120 and the direction of a non-line-of-sight path to the user equipment 120). In some embodiments, the at least one direction is a direction where a signal is to be suppressed.

There could be different ways for the direction estimator 520 to estimate the at least one direction towards the user equipment 120 from the received signal. In some aspects, channel estimation is performed and then a beamforming codebook is applied to find the direction towards the user equipment 120. In particular, in some embodiments, the direction estimator 520 is configured to estimate the direction by application of a beamforming codebook (e.g., using computationally efficient FFT algorithms) to a channel estimate of the received reference signal. In some aspects, the direction is estimated by calculating the maximum of the spatial spectrum estimated from the received signal. In particular, in some embodiments, the direction estimator 520 is configured to estimate the direction by calculating a maximum of a spatial spectrum estimated from the received signal. In some aspects, the estimation depends on the antenna element array, or panel, design. In particular, in some embodiments, the direction is estimated as a function of a physical distance between the antenna elements.

The baseband device 500 comprises an interface 530. The interface 530 is configured to send, to the radio device 420, an indication of the direction towards the user equipment 120. The indication might be sent as a predefined parameter. In some aspects, a single BI is sent over the interface 530. That is, in some embodiments, the indication of the direction is sent as a beam index. In other aspects, one or more explicit directions is/are sent over the interface 530. That is, in some embodiments, the indication of the direction is sent as the direction itself. The interface 530 might support the CPRI protocol, and/or the eCPRI protocol, and/or the ORAN protocol.

In some aspects, the baseband device 500 explicitly or implicitly requests the user equipment 120 to transmit the signal. Therefore, in some embodiments, the baseband device 500 further comprises a transceiver 540 configured to request the user equipment 120 to transmit the signal at least on the aforementioned component carrier CCk.

Aspects of the radio device 420 will be disclosed next with reference to the radio device (RD) 600 in the block diagram of Fig. 6.

The radio device 600 comprises an interface 610. The interface 610 is configured to receive, from the baseband device 500, an indication of a direction towards the user equipment 120. The interface 610 might support the CPRI protocol, and/or the eCPRI protocol, and/or the ORAN protocol. As disclosed above, in some embodiments, the direction is a dominant direction towards the user equipment 120. As further disclosed above, in some embodiments, two or more directions towards the user equipment 120 are estimated, and hence the indication might be of two or more directions towards the user equipment 120. As further disclosed above, in some aspects a single BI is sent over the interface 530 (and thus received over the interface 610). That is, in some embodiments, the indication of the direction is received as a beam index. In other aspects, one or more explicit directions is/are sent over the interface 530 (and thus received over the interface 610). That is, in some embodiments, the indication of the direction is received as the direction itself.

The radio device 600 comprises a beam weight selector 620. In the radio device 600 the indication received from baseband device 500 is mapped to the beam closest (e.g. in pointing direction) to the direction corresponding to the indication for each CC that should be used for transmission to, and/or reception from, the user equipment 120. In particular, the beam weight selector 620 is configured to select beam weights from a beamforming codebook. The beam weights are selected that, out of all beam weights in the beamforming codebook, yield a directional beam that is closest to the direction for at least one component carrier CCk. The codebook can have different sections with beam weights applied to different CCs to compensate for beam squint. In the radio device 600, for each CC or group of CCs, a corresponding table can be available. Due to the frequency difference between CCs, a specific beam pointing might require different beam weights. In particular, in some embodiments, the beam weights are selected based on a carrier frequency of the at least one component carrier CCk. In some aspects, due to the frequency difference between CCs, a specific beam pointing might require different beam vectors. Therefore, in some embodiments, there is one beamforming codebook per each of the at least one component carrier CCk or per each group of at least two component carriers CCi:CCK.

The beam weights can be selected differently depending on whether the indication of the direction is a beam index or the direction itself. When the indication of the direction is a beam index, the beam weights can be selected by using the beam index for a table look-up in the beamforming codebook. When the indication of the direction is the direction itself, the beam weights can be selected by mapping the direction to a beam index and using the beam index for a table look-up in the beamforming codebook. The table look-up might be dependent on the carrier frequency of the at least one component carrier CCk.

If information as in Table 1 is known to the baseband device 500 it is possible for the radio device 600 to map the estimated direction to a beam index (BI). According to Table 1, each beam index is associated with one beam direction (specified in terms of elevation (Elv.) and azimuth (Azi.) angles. In turn, there is one set of N beam weights for each beam direction, where the elevation beam weights for beam index k are denoted Ako, ..., AkN and the azimuth beam weights for beam index k are denoted Bko, ..., BkN. Typically, the beam weights are complex-valued.

Table 1: Example of mapping between beam index, beam direction, and beam weights

The radio device 600 comprises a beamforming network 630. The beamforming network 630 configured to apply the beam weights during communication with the user equipment 120.

Table 1 might comprise not only indices to narrow traffic beam, but also wide beams which could be needed if several user equipment with different (dominant) directions should be scheduled in the same symbol or slot. However, since the physical BI is mapped to a specific direction, the same beam index can be used for all CCs.

Reference is now made to Fig. 7 illustrating a method for beam weight selection for communication with a user equipment 120 as performed by the baseband device 410, 500, 900 according to an embodiment. S104: The baseband device 410, 500, 900 receives, by a receiver 510 in the baseband device 410, 500, 900, a signal from the user equipment 120. The signal is received with the receiver 510 operating on one component carrier CCk in an operational bandwidth.

In this respect, the receiver 510 might not operate on the whole bandwidth of this one component carrier CCk but only on a part, i.e., on a (narrow) frequency part of the component carrier CCk.

S106: The baseband device 410, 500, 900 estimates a direction towards the user equipment 120 from the received signal.

S108: The baseband device 410, 500, 900 sends, over an interface 430, 530 and to the radio device 420, 600, 1000, an indication of the direction towards the user equipment 120.

Embodiments relating to further details of beam weight selection for communication with a user equipment 120 as performed by the baseband device 410, 500, 900 will now be disclosed with continued reference to Fig. 7.

S102: The baseband device 410, 500, 900 requests, by a transceiver 540 in the baseband device 410, 500, 900, the user equipment 120 to transmit the signal at least on the aforementioned one component carrier CCk.

In this respect, it might not be the baseband device 410, 500, 900 itself that actually decides that the user equipment 120 is to transmit the signal at least on the aforementioned one component carrier CCk, or orders the user equipment 120 to transmit the signal at least on the aforementioned one component carrier CCk. Rather, this decision and/or this ordering can be made on a system level where the baseband device 410, 500, 900 merely executes the decision or ordering by requesting the user equipment 120 to transmit the signal at least on the aforementioned one component carrier CCk.

Reference is now made to Fig. 8 illustrating a method for beam weight selection for communication with a user equipment 120 as performed by the radio device 420, 600, 1000 according to an embodiment. S202: The radio device 420, 600, 1000 receives, from the baseband device 410, 500, 900 and over the interface 430, 610, an indication of a direction towards the user equipment 120.

S204: The radio device 420, 600, 1000 selects beam weights from a beamforming codebook. The beam weights are selected that, out of all beam weights in the beamforming codebook, yield a directional beam that is closest to the direction for at least one component carrier CCk.

S206: The radio device 420, 600, 1000 applies, by a beamforming network 200, 630 in the radio device 420, 600, 1000, the beam weights during communication with the user equipment 120.

Fig. 9 schematically illustrates, in terms of a number of functional units, the components of a baseband device 410, 500, 900 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 410a (as in Fig. 11), 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 baseband device 410, 500, 900 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 may be configured to retrieve the set of operations from the storage medium 230 to cause the baseband device 410, 500, 900 to perform the set of operations. The set of operations may be 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 baseband device 410, 500, 900 may further comprise a communications (comm.) interface 220 for communications with other entities, function, nodes, and devices, such as one or more radio devices 420, 600, 1000. As such the communications interface 220 may comprise one or more transmitters and receivers, comprising analogue and digital components. The communications interface 220 might comprise the interface 530. The communications interface 220 might comprise the transceiver 540.

The processing circuitry 210 controls the general operation of the baseband device 410, 500, 900 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 baseband device 410, 500, 900 are omitted in order not to obscure the concepts presented herein. Fig. 10 schematically illustrates, in terms of a number of functional units, the components of a radio device 420, 600, 1000 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 410b (as in Fig. 11), 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 radio device 420, 600, 1000 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 may be configured to retrieve the set of operations from the storage medium 330 to cause the radio device 420, 600, 1000 to perform the set of operations. The set of operations may be 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 radio device 420, 600, 1000 may further comprise a communications interface 320 for communications with other entities, function, nodes, and devices, such as the baseband device 410, 500, 900. As such the communications interface 320 may comprise one or more transmitters and receivers, comprising analogue and digital components. The communications interface 320 might comprise the interface 610.

The processing circuitry 310 controls the general operation of the radio device 420, 600, 1000 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 radio device 420, 600, 1000 are omitted in order not to obscure the concepts presented herein.

Fig. 11 shows one example of a computer program product 410a, 410b comprising computer readable means 430. On this computer readable means 430, a computer program 420a can be stored, which computer program 420a 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 420a and/or computer program product 410a may thus provide means for performing any steps of the baseband device 410, 500, 900 as herein disclosed. On this computer readable means 430, a computer program 420b can be stored, which computer program 420b 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 420b and/or computer program product 410b may thus provide means for performing any steps of the radio device 420, 600, 1000 as herein disclosed.

In the example of Fig. 11, the computer program product 410a, 410b 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 410a, 410b 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 420a, 420b is here schematically shown as a track on the depicted optical disk, the computer program 420a, 420b can be stored in anyway which is suitable for the computer program product 410a, 410b.

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 baseband device (410, 500, 900) for beam weight selection for communication with a user equipment (120), the baseband device (410, 500, 900) comprising: a receiver (510) configured to receive a signal from the user equipment (120), wherein the signal is received with the receiver (510) operating on one component carrier (CCk) in an operational bandwidth; a direction estimator (520) configured to estimate a direction towards the user equipment (120) from the received signal; and an interface (430, 530) configured to send, to a radio device (420, 600, 1000), an indication of the direction towards the user equipment (120).

2. The baseband device (410, 500, 900) according to claim 1, wherein the baseband device (410, 500, 900) further comprises: a transceiver (540) configured to request the user equipment (120) to transmit the signal at least on said one component carrier (CCk).

3. The baseband device (410, 500, 900) according to claim 1, wherein the direction estimator (520) is configured to estimate the direction by application of a beamforming codebook to a channel estimate of the received reference signal.

4. The baseband device (410, 500, 900) according to claim 1, wherein the direction estimator (520) is configured to estimate the direction by calculating a maximum of a spatial spectrum estimated from the received signal.

5. The baseband device (410, 500, 900) according to claim 1, wherein the indication of the direction is sent as a beam index.

6. The baseband device (410, 500, 900) according to claim 1, wherein the indication of the direction is sent as the direction itself.

7. The baseband device (410, 500, 900) according to claim 1, wherein the receiver (510) is a narrowband receiver.

8. The baseband device (410, 500, 900) according to claim 7, wherein the receiver (510) is configured to have access to all antennas at which the signal is wirelessly received, but only within the operational bandwidth.

9. The baseband device (410, 500, 900) according to claim 8, wherein the direction is estimated as a function of a physical distance between the antennas.

10. The baseband device (410, 500, 900) according to any preceding claim, wherein the direction is a dominant direction towards the user equipment (120).

11. A radio device (420, 600, 1000) for beam weight selection for communication with a user equipment (120), the radio device (420, 600, 1000) comprising: an interface (430, 610) configured to receive, from a baseband device (410, 500, 900), an indication of a direction towards the user equipment (120); a beam weight selector (620) configured to select beam weights from a beamforming codebook, wherein the beam weights are selected that, out of all beam weights in the beamforming codebook, yield a directional beam that is closest to the direction for at least one component carrier (CCk); and a beamforming network (200, 630) configured to apply the beam weights during communication with the user equipment (120).

12. The radio device (420, 600, 1000) according to claim 11, wherein the beam weights are selected based on a carrier frequency of the at least one component carrier (CCk).

13. The radio device (420, 600, 1000) according to claim 11, wherein there is one beamforming codebook per each of the at least one component carrier (CCk) or per each group of at least two component carriers (CC1:CCK).

14. The radio device (420, 600, 1000) according to claim 11, wherein the indication of the direction is a beam index, and wherein the beam weights are selected by using the beam index for a table look-up in the beamforming codebook.

15. The radio device (420, 600, 1000) according to claim 11, wherein the indication of the direction is the direction itself, and wherein the beam weights are selected by mapping the direction to a beam index, and using the beam index for a table look-up in the beamforming codebook.

16. The radio device (420, 600, 1000) according to claim 14, or 15, wherein the table look-up is dependent on a carrier frequency of the at least one component carrier (CCk).

17. The baseband device (410, 500, 900) according to any of claims 11 to 16, wherein the direction is a dominant direction towards the user equipment (120).

18. A network node (110, 400) for beam weight selection for communication with a user equipment (120), the network node (110, 400) comprising a baseband device (410, 500, 900) according to any of claims 1 to 10 and a radio device (420, 600, 1000) according to any of claims 11 to 17.

19. A method for beam weight selection for communication with a user equipment (120), the method being performed by a baseband device (410, 500, 900), the method comprising: receiving (S104), by a receiver (510) in the baseband device (410, 500, 900), a signal from the user equipment (120), wherein the signal is received with the receiver (510) operating on one component carrier (CCk) in an operational bandwidth; estimating (S106) a direction towards the user equipment (120) from the received signal; and sending (S108), over an interface (430, 530) and to a radio device (420, 600, 1000), an indication of the direction towards the user equipment (120).

20. A method for beam weight selection for communication with a user equipment (120), the method being performed by a radio device (420, 600, 1000), the method comprising: receiving (S202), from a baseband device (410, 500, 900) and over an interface (430, 610), an indication of a direction towards the user equipment (120); selecting (S204) beam weights from a beamforming codebook, wherein the beam weights are selected that, out of all beam weights in the beamforming codebook, yield a directional beam that is closest to the direction for at least one component carrier (CCk); and applying (S206), by a beamforming network (200, 630) in the radio device (420, 600, 1000), the beam weights during communication with the user equipment (120).

21. A computer program (1120a) for beam weight selection for communication with a user equipment (120), the computer program comprising computer code which, when run on processing circuitry (910) of a baseband device (410, 500, 900), causes the baseband device (410, 500, 900) to: receive (S104), by a receiver (510) in the baseband device (410, 500, 900), a signal from the user equipment (120), wherein the signal is received with the receiver (510) operating on one component carrier (CCk) in an operational bandwidth; estimate (S106) a direction towards the user equipment (120) from the received signal; and send (S108), over an interface (430, 530) and to a radio device (420, 600, 1000), an indication of the direction towards the user equipment (120).

22. A computer program (1120b) for beam weight selection for communication with a user equipment (120), the computer program comprising computer code which, when run on processing circuitry (1010) of a radio device (420, 600, 1000), causes the radio device (420, 600, 1000) to: receive (S202), from a baseband device (410, 500, 900) and over an interface (430, 610), an indication of a direction towards the user equipment (120); select (S204) beam weights from a beamforming codebook, wherein the beam weights are selected that, out of all beam weights in the beamforming codebook, yield a directional beam that is closest to the direction for at least one component carrier (CCk); and apply (S206), by a beamforming network (200, 630) in the radio device (420, 600, 1000), the beam weights during communication with the user equipment (120).

23. A computer program product (nioa, mob) comprising a computer program (420a, 420b) according to at least one of claims 21 and 22, and a computer readable storage medium (1130) on which the computer program is stored.