WO2023110403A1 - Coverage-enhancing device with single antenna array - Google Patents

Abstract

A coverage-enhancing device (20), comprising: a single antenna array (214) having a plurality of antennas (Am, Ak) configured to receive and transmit radio frequency (RF) signals; and signal processing circuitry (50) comprising: a signal input mechanism (52) configured to provide at least one summed signal (SR1, SR2) based on RF signals received at said plurality of antennas, dependent on at least one receive parameter of the received RF signal; a combinatorial network (53) configured to provide at least one signal output component (ST1) related to a predetermined transmit parameter which is associated with a predetermined receive parameter, based on the at least one summed signal (SR1, SR2); a signal output mechanism (54) configured to apply said signal output component to said plurality of antennas, to transmit an output RF signal based on the predetermined transmit parameter.

Description

COVERAGE-ENHANCING DEVICE WITH SINGLE ANTENNA ARRAY

Technical field

This disclosure is related to solutions in the context of wireless communication between radio nodes of a wireless system, such as between different wireless devices or between a wireless device and an access node of a wireless network. Specifically, solutions are provided for a coverage-enhancing device, operable to relay communication between radio nodes.

Background

Various protocols and technical requirements for wireless communication have been standardized under supervision of inter alia the 3rd Generation Partnership Project (3GPP). Improvement and further development are continuously carried out, and new or amended functions and features are thus implemented in successive releases of the technical specifications providing the framework for wireless communication.

Wireless communication may in various scenarios be carried out between a wireless network and a wireless device. The wireless network typically comprises an access network including a plurality of access nodes, which historically have been referred to as base stations. In a 5G radio access network such a base station may be referred to as a gNB. Each access node may be configured to serve one or more cells of a cellular wireless network. A variety of different types of wireless devices may be configured to communicate with the access network, and such wireless devices are generally referred to as User Equipment (UE). Communication which involves transmission from the UE and reception in the wireless network is generally referred to as Uplink (UL) communication, whereas communication which involves transmission from the wireless network and reception in the UE is generally referred to as Downlink (DL) communication. In various scenarios, the UE may be configured to communicate directly with another wireless device. This may for certain applications be referred to as sidelink communication in 3GPP specifications.

In order to increase or improve coverage of a wireless network, a coverageenhancing device may be employed. This may e.g. be the case near a cell edge, or where an environment causes problems of maintaining a sufficiently strong or reliable access link between the wireless network and wireless devices. The coverage-enhancing device is a device configured to forward radio signals. In some realizations, the coverageenhancing device may be a passive device, configured to reflect or possibly redirect, an incoming signal. Alternatively, the coverage-enhancing device may be configured to amplify and transmit a received radio signal. In either case, the coverage-enhancing device is configured to receive a signal from a first direction and transmit a signal in a second direction. Various types of coverage-enhancing devices are occasionally referred to as smart repeaters (SR), which can be thought of as a traditional relay node but where some intelligence is added. In particular, such a coverage-enhancing device may be capable of performing beamforming, both in the direction of the transmitting radio node(s) and in the direction of the receiving radio node(s).

The typical use case for a coverage-enhancing device is to provide coverage extensions and, therefore, they are thought of as having two antenna arrays. A front array is directed towards an access node, e.g. a gNB, and a back array is directed towards a zone where coverage is low. When there is receive beamforming at the front array for DL operation, the output signal is then amplified and transferred to the back array, which performs transmit beamforming towards a UE present in said zone. The UL works in a verbatim manner, but where the front and back array switch roles.

A drawback associated with a coverage-enhancing device with two antenna arrays is a high level of complexity and resulting cost of manufacture and deployment.

Summary

In view of the foregoing, solutions are presented herein for a coverage-enhancing device which overcomes one or more problems associated with the state of the art. According to one aspect, the proposed solution provides a less complex design than prior art solutions, by providing a single array coverage-enhancing device. In various examples, the proposed solution provides a single array coverage-enhancing device capable of not only point-to-point functionality, but also for reciprocal operation between a plurality of nodes, beam-splitting, and beam collection.

The invention is defined by the independent claims. According to one aspect, the proposed solution relates to a coverage-enhancing device, comprising: a single antenna array having a plurality of antennas configured to receive and transmit radio frequency, RF, signals; and signal processing circuitry comprising: a signal input mechanism configured to provide at least one summed signal based on RF signals received at said plurality of antennas, dependent on at least one receive parameter of the received RF signal; a combinatorial network configured to provide at least one signal output component related to a predetermined transmit parameter which is associated with a predetermined receive parameter, based on the at least one summed signal; a signal output mechanism configured to apply said signal output component to said plurality of antennas, to transmit an output RF signal based on the predetermined transmit parameter.

By means of the proposed solution, association between predetermined receive parameter configuration and predetermined transmit parameter configuration leads to strong RF reflections between related directions of arrival and departure, while other directions are attenuated.

Brief description of the drawings

Fig. 1 schematically illustrates an implementation of a wireless communication system, in which a UE communicates with a radio node, such as an access node of a wireless network, over a coverage-enhancing device.

Fig. 2 schematically illustrates a coverage-enhancing device configured to operate with the wireless network according to various examples.

Fig. 3 schematically illustrates four use cases for a coverage-enhancing device according to the proposed solution.

Fig. 4 schematically illustrates reflection patterns related to the use cases of Fig. 3 Fig. 5 illustrates a coverage-enhancing device according to the proposed solution. Fig. 6 illustrates various aspect of a first stage part of an implementation of the coverage-enhancing device of Fig. 5. Fig. 7 illustrates various aspect of a second stage part of an implementation of the coverage-enhancing device of Fig. 5.

Fig. 8 schematically illustrates possible reflection angle pairs for an example of a configuration of the coverage-enhancing device.

Fig. 9 illustrates an example of an analog implementation of the proposed coverage-enhancing device.

Fig. 10 shows a flow chart of a method according to an example of the proposed solution.

Detailed description

In the following description, for purposes of explanation and not limitation, details are set forth herein related to various examples. However, it will be apparent to those skilled in the art that the present invention may be practiced in other examples that depart from these specific details. In some instances, detailed descriptions of well- known devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail. The functions of the various elements including functional blocks, including but not limited to those labeled or described as “computer”, “processor” or “controller”, may be provided through the use of hardware such as circuit hardware and/or hardware capable of executing software in the form of coded instructions stored on computer readable medium. Thus, such functions and illustrated functional blocks are to be understood as being either hardware-implemented and/or computer-implemented and are thus machine-implemented. In terms of hardware implementation, the functional blocks may include or encompass, without limitation, digital signal processor (DSP) hardware, reduced instruction set processor, hardware (e.g., digital or analog) circuitry including but not limited to application specific integrated circuit(s) (ASIC), and (where appropriate) state machines capable of performing such functions. In terms of computer implementation, a computer is generally understood to comprise one or more processors or one or more controllers, and the terms computer and processor and controller may be employed interchangeably herein. When provided by a computer or processor or controller, the functions may be provided by a single dedicated computer or processor or controller, by a single shared computer or processor or controller, or by a plurality of individual computers or processors or controllers, some of which may be shared or distributed. Moreover, use of the term “processor” or “controller” shall also be construed to refer to other hardware capable of performing such functions and/or executing software, such as the example hardware recited above.

The drawings are to be regarded as being schematic representations and elements illustrated in the drawings are not necessarily shown to scale. Rather, the various elements are represented such that their function and general purpose become apparent to a person skilled in the art. Any connection or coupling between functional blocks, devices, components, or other physical or functional units shown in the drawings or described herein may also be implemented by an indirect connection or coupling. A coupling between components may also be established over a wireless connection. Functional blocks may be implemented in hardware, firmware, software, or a combination thereof. The terms “receive” or “receiving” data or information shall be understood as “detecting, from a received signal”.

Fig. 1 illustrates a high-level perspective of operation in a wireless system, wherein a UE 10 is configured to communicate with a wireless network 100. The wireless network 100 may be a radio communication network 100, configured to operate under the provisions of technical specifications specified by 3GPP, such as for 5G NR or any future releases, according to various examples outlined herein. The wireless network 100 may comprise a core network 110, which in turn may comprise a plurality of core network nodes. The core network is connected to at least one access network 120 comprising one or more base stations or access nodes, of which access nodes 121-123 are illustrated. Each access node 121-123 is a radio node configured for wireless communication on a physical channel with various UEs, of which UEs 10 and 11 are shown. The core network 110 may in turn be connected to other networks 130. A coverage-enhancing device 20 is configured to operate in the wireless network 100, to repeat signals between various radio nodes of the wireless system, such as between the wireless network and at least one wireless device. The coverage-enhancing device 20 may in this context be configured by the wireless network 100, such as by a hosting base access node 121, to operate in accordance with a certain UL/DL TDD scheme, and within a certain frequency range. Before discussing further details and aspects of the proposed method, functional elements for the coverage-enhancing device 20 configured to carry out the proposed solution, will be briefly discussed.

Fig. 2 schematically illustrates an example of the coverage-enhancing device 20 for use in a wireless network 100 as presented herein, and for carrying out various method steps as outlined.

The coverage-enhancing device 20 comprises a transceiver 213 for communicating with other entities of the radio communication network 100, such as with the access node 121 and the UE 10, in different frequency bands. The transceiver 213 may thus include at least one radio unit, and optionally two or more radio units, for communicating through an air interface. Each radio unit may, in turn, comprise an amplifier unit, configured to amplify a received signal before transmitting the amplified signal. For operation as a coverage-enhancing device towards one or more UEs, each radio unit may act as an analog pass-through, and is controlled to receive and transmit (and possibly amplify) a signal without decoding or data manipulation.

The coverage-enhancing device 20 further comprises a single antenna array 214, which as such includes a plurality of antennas, such as M antennas AI-AM. The antenna array 214 may be configured for operation of different beams in transmission and/or reception.

The coverage-enhancing device 20 further comprises logic circuitry 210 configured to communicate, via the radio transceiver, with a hosting node of the wireless network 100, such as the access node 121. The logic circuitry 210 may be configured to encode and decode control signaling within communication with the wireless network 100. The logic circuitry 210 may also be configured to control the transceiver 213 and possibly the antenna system 214 to transmit and receive dedicated and/or broadcasted signals for such control signaling between the wireless network 100 and the coverage-enhancing device 20. This may involve receiving control signals for operation of the transceiver 213 and transmitting information to the access node 121. Received control signals may comprise control information associated with TDD configuration for UL/DL switching, beamforming configuration for controlling the antenna system 214, on/off information for controlling operation activity of the coverage-enhancing device 20, frequency band configuration, etc. The logic circuitry 210 is further configured to control the transceiver 213, and possibly the antenna system 214, to operate according to received control signals, or in accordance with one or more predetermined rules or switching schemes.

The logic circuitry 210 may include a processing device 211, including one or multiple processors, microprocessors, data processors, co-processors, and/or some other type of component that interprets and/or executes instructions and/or data. The processing device 211 may be implemented as hardware (e.g., a microprocessor, etc.) or a combination of hardware and software (e.g., a system-on-chip (SoC), an applicationspecific integrated circuit (ASIC), etc.). The processing device 211 may be configured to perform one or multiple operations based on an operating system and/or various applications or programs.

The logic circuitry 210 may further include memory storage 212, which may include one or multiple memories and/or one or multiple other types of storage mediums. For example, the memory storage 212 may include a random access memory (RAM), a dynamic random access memory (DRAM), a cache, a read only memory (ROM), a programmable read only memory (PROM), flash memory, and/or some other type of memory. The memory storage 212 may include a hard disk (e.g., a magnetic disk, an optical disk, a magneto-optic disk, a solid state disk, etc.). The memory storage 212 is configured for holding computer program code, which may be executed by the processing device 211, wherein the logic circuitry 210 is configured to control the UE 10 to carry out any of the method steps as provided herein. Software defined by said computer program code may include an application or a program that provides a function and/or a process. The software may include device firmware, an operating system (OS), or a variety of applications that may execute in the logic circuitry 210.

Obviously, the coverage-enhancing device 20 may include other features and elements than those shown in the drawing or described herein, such as a power supply, a casing, sensors, etc., but these are left out for the sake of simplicity. Further features and functions of the coverage-enhancing device 20 will be discussed below. For the sake of brevity, the coverage-enhancing device 20 will be referred to below by its abbreviation CED.

It may be noted that it is not obvious how to design an CED 20 having a single antenna array, or panel, 214. For the case of TDD systems there are two approaches that can be used if the CED can operate in either Rx or Tx mode (half duplex): 1. The straightforward solution is to operate in half-duplex mode, and first receive a signal, buffer it, and then transmit the signal in the next slot. This yields a rate loss of 50%.

2. If the CED instead is receiving from all connected nodes (UEs and gNBs) in a first slot, buffering the data, and then transmit in a next slot, the rate could be maintained but, UL/DL timing would need to be re-defined and UEs connected via the CED would need to transmit in the system DL slots and receive in the system UL slots. This would cause interference to other UEs in the same cell, and to neighboring cells in general.

If the CED can operate in full duplex the UL/DL timing can be maintained. The challenge is then typically to ensure that the CED is synchronized with the network. This requires synchronization signals as well as timing advance signaling.

The proposed solution addresses the challenge of obtaining propagation paths between arbitrary multiple network nodes via a single antenna array while avoiding parasitic reflections. In this context, a typical CED can be understood as a reflecting metal surface where the tilting angles determine how an incoming signal is reflected. It therefore follows that an incoming signal from an arbitrary direction may have an associated reflection angle, this being known as a parasitic reflection. The proposed solution inter alia mitigates such effects and enables the CED to strongly reflect signals only between configured angles, while other signals are diffusely scattered. The objectives of obtaining propagation paths between arbitrary multiple network nodes via a single antenna array are further clarified with reference to four different use case examples of the single array CED 20, provided in Fig. 3.

In the top left corner of Fig. 3, a use case is shown where the CED 20 should split the incoming signal, from an access node 121, and transmit it to two different UEs 10, 11. Such a scenario can be, e.g., useful for broadcast and/or CDMA/TDMA or FDMA type signals (i.e. not SDMA). This use case may be referred to as beam splitting.

In the top right corner, the corresponding uplink scenario is shown, where the signals sent by two UEs 10, 11 should be superimposed and then sent to the same access node 121, such as a gNB. It may be noted that the CED configurations in the two top pictures are not necessarily the same. The use case of the top right corner may be referred to as beam collection. In the bottom left corner, a use case is shown where one gNB 121 should transmit signals to a UE 10, while another gNB 122 should transmit to another UE 11. As will be shown, the single array CED 20 according to the proposed solution handles such a use case too.

Finally, in the bottom right corner, a reciprocal CED use case is shown, which essentially means that it can cover both use cases at the top of the drawing simultaneously. Or, in other words, no configuration change needs to take place at the CED 20 for handling both cases. A technical effect of this is that there need not be any synchronization at the CED 20 with respect to UL/DL patterns in the traffic. Moreover, the single array CED 20 according to the proposed solution is reciprocal for any use case.

Fig. 4 schematically shows reflection patterns corresponding to the use cases of Fig. 3. The reflection pattern examples are provided at the same corner of the respective drawings, i.e. the top left corner reflection pattern of Fig. 4 corresponds to the top left corner use case of Fig. 3, and so on. The horizontal axis of the reflection pattern diagrams refer to the angle of arrival (Ao A) to the antenna 214, whereas the vertical axis refers to angle of departure (AoD) from the antenna 214. Note that the axes are “conceptual” as each angle is in fact a spherical angle specified by two real numbers (azimuth and elevation).

In the two top cases of Figs 3 and 4, the angular direction to the gNB 121 is a and the angles to the two UEs 10, 11 are

and ₂ respectively (all three angles being spherical angles). In the two bottom cases of Figs 3 and 4, the intended reflection power further identifies angles to the two gNBs 121 and 122 as a and a₂ respectively.

Based on the use cases identified in Figs 3 and 4, it may be identified that the proposed solution targets the objective of how to build a one-array CED 20 in the most efficient way, that produces K arbitrarily selected “points” of reflection in a plot similar to those of Fig. 4. Note that for the simplest use case, with communication between two nodes via the CED, two “points” are needed to support communication in both directions to obtain reciprocity. The points shall then have locations where they are mirrored in the diagonal going from lower left to upper right. The bottom right diagram in Fig. 4 thus shows a case where, inter alia, the node in angle a can communicate, in both directions, with nodes located at both f and E. Fig. 5 provides a schematic and logical representation of the CED 20 according to the proposed solution. This relates to a coverage-enhancing device 20, comprising a single antenna array 214 having a plurality of antennas, of which antennas A_m and Ak are indicated, configured to receive and transmit RF signals. Each antenna is connected to signal processing circuitry 50. The signal processing circuitry 50 may be configured to realize a spatial filter, to determine transmission characteristics of a transmitted RF signal dependent on receive characteristics of a received RF signal.

The signal processing circuitry 50 comprises a signal input mechanism 52 configured to provide at least one summed signal SR based on RF signals received at said plurality of antennas, dependent on at least one receive parameter of the received RF signal.

The signal input mechanism 52 is connected to a combinatorial network 53, configured to provide at least one signal output component ST related to a predetermined transmit parameter which is associated with a predetermined receive parameter, based on the at least one summed signal SR.

The combinatorial network 53 is connected to a signal output mechanism 54, configured to apply said signal output component to said plurality of antennas A_m, Ak to transmit an output RF signal based on the predetermined transmit parameter.

By summing signals from the antenna to obtain one or more summed signals dependent on a receive parameter, and providing signal output components for a predetermined transmit parameter associated with a predetermined receive parameter, strong reflections will only be obtained where the predetermined receive parameter and the predetermined transmit parameter correspond. In this context, said parameters may be one or more spatial parameters for the received and transmitted RF signal, respectively. In some examples, the receive parameter is indicative of the AoA, whereas the transmit parameter is indicative of AoD. According to the proposed solution, the signal input mechanism 52 operates as a receive spatial filter, whereas the signal output mechanism 54 operates as a transmit spatial filter.

As noted, the proposed solution is in some examples configured to support reciprocal operation between plural radio nodes. Let K_A and K_D denote the number of AoAs and AoDs, respectively, that the CED 20 shall support. For the four use cases from before, described with reference to Figs 3 and 4, we have (A_A, K_D) = (1,2) for the first (top left) use case, (A_A, K_D) = (2,1) for the second (top right) use case, (K_A, K_D) = (2,2) for the third (bottom left) use case and (/<_A, K_D) = (3,3) for the fourth (bottom right) use case. Note that the product of K_A and K_D is not the number of “points” in the figures; rather the product gives the maximum number of points that one can put out with K_A AoAs and K_D AoDs.

Fig. 6 schematically illustrates circuitry associated with one single antenna m, according to an example of the proposed solution. All antennas would, however, have the corresponding circuitry. Each antenna is connected to a circulator 51. The other two circulator ports are connected to two boxes; Box AoA_m serving as an input unit for a received RF signal, and Box AoD_m serving as an output unit for an RF signal to be transmitted. The former box has K_A outputs and forms a part of the signal input mechanism 52. The latter box has K_D inputs and forms a part of the signal output mechanism 54. In the drawing, signals flow from left to right for the “AoA” boxes, but from right to left for the “AoD” boxes. The later stage of the implementation, labeled “connection switch” in Fig. 6, comprises the combinatorial network 53 and further functional elements of the signal input mechanism 52 and of the signal output mechanism 54 that are connected to all antennas, as will be explained below. The implementation of each box is shown in the bottom part of Fig. 6. For the “AoA” boxes, the heavy solid dot 61 is a signal splitter.

The AoA boxes may be configured to phase rotate and/or amplitude scale the received signal to obtain input component signals corresponding to each of at least one predetermined receive parameter. According to some examples, for each antenna A_m, the AoA box is phase rotating the incoming signal in K_A different ways according to phase values

Similarly, the AoD boxes may be configured to combine the signal output component for each of at least one predetermined transmit parameter at each antenna A_m. In some examples the AoD box phase rotates the K_D inputs according to phase values and then sums the outputs. The phase values ultimately specify the

AoA and AoD angles that the single antenna array CED 20 supports.

Fig. 7 shows, for the sake of simplicity, the singe antenna array CED 20 where only two antennas A_m and Ak are indicated. Nevertheless, this drawing will be referred to for further describing the next stage of the implementation, wherein all the M antennas of the antenna array 214 interplay. This involves, as mentioned, summation in the signal input mechanism 52 to obtain at least one summed signal.

The first output of the input units 701, 702, i.e. AoA boxes, for all M antennas are summed at the very top summation member 711. Also the second indicated output of the AoA boxes, i.e. the K_A th output, for all M antennas are separately summed, at the summation member 712. In the drawing, only two signals (originating from antennas m and k) are summed, but there would be M incoming signals to each summation member 711, 712. All such summation members 711, 712 form a summation unit which is a functional component of the signal input mechanism 52 as shown in Fig. 5. The summation unit is configured to provide in K_A summed signals SRI, SR2, each being dependent on at least one receive parameter of the received RF signal, indicative of a spatial character of the received RF signal. As an example, each input unit 701, 702 is configured to pass on, to a common summation unit 711, a signal associated with a spatial character corresponding to one predetermined AoA. To the right, i.e. downstream, of the summation units 711, 712, there are K_A summed signals, of which SRI, SR2 are shown.

The K_A summed signals SRI, SR2, are then transformed into K_D signals, here referred to as output components ST, by the combinatorial network 53, as will be further described below. In the drawing, two output components STI, ST2 are shown by way of example.

The first output component STI provided by the combinatorial network 53 is subsequently split, or divided, into M signals, illustrated by the top heavy black dot 721. The M so created signals (all of which are the same) are then provided as the first input at all output units 731, 732, i.e. the AoD boxes. Similarly, also the second output component ST2 provided by the combinatorial network 53 is split into M signals, which are in turn used as the second inputs at the AoD boxes 731, 732. Each signal divider 721, 722 form part of a splitter unit, which is a functional component of the signal output mechanism 54. The splitting units are configured to convert each of the K_D output components into M separate signals provided to each one output unit 731, 732. The K_Dth output component is used as the K_Dth input to the respective output unit 731, 732.

The foregoing description with reference to Figs 5-7 has provided a logical implementation of the single array CED 20, which is capable of operating in accordance with the objectives as set out with reference to Figs 3 and 4. The following provides further detailed description on how this is accomplished.

The phases the set of all phases across the M antennas that relate

to output k of the AoA boxes, or input units) is selected such that, after summation, only signals that arrive from direction a_k will add coherently. For any other direction, the signal amplitude would be (nearly) zero after the summation. This is in fact easily done by selecting the set as phases from a, so-called, steering vector

corresponding to a_k . The K_A signals entering the combinatorial network are therefore the signals that arrive from K_A directions a , ... , a_KA. This can also be stated as “the AoA boxes together with the summation blocks ‘look’ in K_A spatial directions”. In this context, each summation operation means applying an input spatial filter corresponding to one spatial characteristic, such as one AoA. The summation results in signal components corresponding to other AoAs being suppressed.

Likewise, the K_D signals leaving the combinatorial network are being transmitted

These directions are being specified by the phases k = 1, ... , KQ. SO, the first output of the combinatorial network will be

radiated towards spatial direction /3₁, etc. In this context, by supplying the output components to the corresponding input of the output units 731, 732 (AoD boxes), an output spatial filter associated with the input spatial filter, is obtained.

Fig. 8 schematically illustrates reflection power and possible reflection angle-pairs for an example of a single antenna array CED 20 according to the proposed solution, with K_A = 2 and K_D = 3. No matter what the combinatorial network 53 does, the above discussion implies that strong reflections can only be located at the intersections of the dashed lines. The reason being that we can only receive signals from the a_k directions, and we can only radiate along the [3_k directions. The intended functionality of the combinatorial network 53 is now to put out the reflection points on the grid according to the use case.

Various connections configured in the combinatorial network 53 specify which of the K_A summed signals are connected to generate which of the K_D output components. In this context, the combinatorial network 53 may comprise a circuit configured to combine at least two summed signals SRI, SR2 related to different predetermined receive parameters to provide at least one signal output component STI related to a predetermined transmit parameter associated with the predetermined receive parameters. Alternatively, or additionally, the combinatorial network may comprise a circuit configured to provide at least two signal output components STI, ST2 related to different predetermined transmit parameters, based on a summed signal SRI related to an associated first predetermined receive parameter.

According to one example, a fully digital implementation of the signal processing circuitry 50 may be provided. This may include providing an analog-to-digital converter (ADC) between the output ports of each circulator and the input units (Ao A boxes) 701, 702), and a digital-to-analog converter (DAC) between the input ports of each circulator and the output units (AoD boxes) 731, 732. In some examples, the signal processing circuitry 50 is provided with a full RF chain, including down/up conversion etc.

According to another example, a hybrid analog/digital implementation is provided. In such an example, ADCs and DACs are placed at the input/output of the combinatorial network 53, which is then implemented in the digital domain. Compared to the fully digital implementation, a significant reduction in the number of ADCs and DACs is obtained (from M ADCs and M DACs down to K_A ADCs and K_D DACs). Moreover, the signal level at the ADCs/DACs would be larger, which is better from a noise perspective, as the full antenna array-gain is achieved without adding noise. The implementation of the phase shifters of the input units 701, 702 and output units 731, 732 will be detailed further in the next example. Like the fully digital approach, delay caused by the signal processing and the dissipated power could be challenging.

Fig. 9 shows an example of an analog implementation of the proposed solution. In general, the phase shifting function of the AoA and AoD boxes, corresponding to input units 701, 702 and output units 731, 732 of Fig 7, can be implemented with variable capacitors, a combination of inductors and capacitors, inductors only, or variable “paths”. All of these are known. They may be continuously tunable, or in discrete steps, implemented e.g. with switches that select different values that influence the phase.

At each point where the signal is split or combined, extra attention is needed to ensure the circuitry operates as intended. In particular:

1. At the output of the circulator the impedance is typically 50 Ohm. If the signal is divided into different paths in the AoA boxes, as illustrated in the upper logical implementation of Fig. 6, a power drop can be expected. To avoid this a buffer amplifier/impedance converter 91 may be used. It serves the purposes of ensuring that the output of the circulator sees a constant load impedance and that the signals to each group of phase shifters are not interfering with each other., e.g., by using amplifiers with multiple outputs to feed each phase shifter (e.g in 701 in Figure 7) or by using amplifiers with low output impedance compared to the impedance loading the phase shifters (this can be understood as avoiding that the signals go backwards through the phase shifters).

2. When combining the signals before entering the circulator, as illustrated in the lower logical implementation of Fig. 6, the impedance again needs to be defined, to e.g. 50 Ohm. For this purpose, an impedance transformer 92 is provided to ensure the 50 Ohm at the input to the circulator, and to prevent interference between the KD steering vectors (i.e. signal going backwards similar to the problem in the receive side). The input of the buffer amplifier needs to have a low impedance compared to the impedance at the opposite side of the phase- shifters alternatively multiple input ports connected to each phase-shifter in 731 (and inherently sum the signals).

The combinatorial network 53 may be implemented with switches, to associate receive angles (AoA) with transmit angles (AoD) arbitrarily. Additionally, logic functions for adding (combining) or splitting and possibly buffer amplifiers may be needed. Further, hybrid couplers can be used to obtain the logic features of the combinatorial network, further buffer amplifiers or impedance converters may then be needed to ensure the impedance (e.g. 50 Ohm) at the feeds of the hybrid coupler. The summation 93 of signals may be implemented as a multi input buffer amplifier.

According to one aspect, the proposed solution provides a method for operating a coverage-enhancing device 20 comprising a single antenna array 214 having a plurality of antennas. An example of this method is outlined in the flow chart of Fig. 10, and comprises the following method elements:

At 1010, the coverage-enhancing device 20 receives an RF signal at said antennas.

At 1020, the coverage-enhancing device 20 determines at least one summed signal based on the received RF signals dependent on at least one receive parameter;

At 1030, the coverage-enhancing device 20 determines at least one signal output component related to at least one predetermined transmit parameter which is associated with at least one predetermined receive parameter, based on the at least one summed signal. At 1040, the coverage-enhancing device 20 applies said at least one signal output component to a signal output mechanism connected to said plurality of antennas to transmit an RF signal dependent on the at least one predetermined transmit parameter.

In the foregoing, various aspects of the proposed solution have been outlined, and examples of implementations have been provided. The proposed solution involves a single panel, or antenna array, CED 20 with independent treatment (e.g., signal paths) of at least one predetermined receive parameter configuration and at least one predetermined transmit parameter configuration, and in particular where the sum of the number of receive parameter configurations and transmit parameter configurations is at least three. Each parameter configuration may be associated with a spatial characteristic, such as an AoA or AoD. By means of the proposed solution, the configured correspondence between the predetermined receive parameter configuration and the predetermined transmit parameter configuration, e.g. providing associated AoA- AoD pairs, are the sole angles where reflections take place and where impinging signals from other directions are attenuated.

The proposed solution may be provided in any form as provided in the following items.

Item 1. A coverage-enhancing device (20), comprising: a single antenna array (214) having a plurality of antennas (A_m, Ak) configured to receive and transmit radio frequency, RF, signals; and signal processing circuitry (50) comprising: a signal input mechanism (52) configured to provide at least one summed signal (SRI, SRI) based on RF signals received at said plurality of antennas, dependent on at least one receive parameter of the received RF signal; a combinatorial network (53) configured to provide at least one signal output component (STI) related to a predetermined transmit parameter which is associated with a predetermined receive parameter, based on the at least one summed signal (SRI, SRI); a signal output mechanism (54) configured to apply said signal output component to said plurality of antennas, to transmit an output RF signal based on the predetermined transmit parameter. Item 2. The coverage-enhancing device of item 1, wherein the signal input mechanism is configured to provide a first number (KA) of summed signals, each summed signal corresponding to a respective predetermined receive parameter.

Item 3. The coverage-enhancing device of item 2, wherein the combinatorial network is configured to provide a second number (KD) of signal output components, each signal output component corresponding to a respective predetermined transmit parameter.

Item 4. The coverage-enhancing device of item 3, wherein the sum of the first number (KA) and the second number (KD) is at least three.

Item 5. The coverage-enhancing device of any preceding item, wherein the combinatorial network (120) comprises a circuit, configured to combine at least two summed signals (SRI, SRI) related to different predetermined receive parameters to provide at least one signal output component (STI) related to a predetermined transmit parameter associated with the predetermined receive parameters.

Item 6. The coverage-enhancing device of any preceding item, wherein the combinatorial network comprises a circuit, configured to provide at least two signal output components (STI, STI) related to different predetermined transmit parameter configuration, based on a summed signal (SRI) related to an associated first predetermined receive parameter.

Item 7. The coverage-enhancing device of any preceding item, wherein the signal input mechanism comprises, for each antenna, an input unit (701, 702) configured to phase rotate and/or amplitude scale the received signal to obtain input component signals corresponding to each of at least one predetermined receive parameter.

Item 8. The coverage-enhancing device of item 7, wherein the input units are connected to a summation unit (711, 712), configured to sum the input component signals corresponding to the same predetermined receive parameter from said antennas.

Item 9. The coverage-enhancing device of any preceding item, wherein the signal output mechanism (54) is configured to combine the signal output component for each of at least one predetermined transmit parameter at each of the plurality of antennas.

Item 10. The coverage-enhancing device of item 9, wherein the output mechanism is configured to provide the output component to each of said output units.

Item 11. The coverage-enhancing device of any preceding item, wherein the receive parameter is indicative of an angle of arrival, AoA, of the received RF signal. Item 12. The coverage-enhancing device of any preceding item, wherein the transmit parameter is indicative of an angle of departure, AoD, of the transmitted RF signal.

Item 13. The coverage-enhancing device of any preceding item, comprising: at each antenna, a circulator (51) connecting the antenna with said input mechanism and said output mechanism.

Item 14. The coverage-enhancing device of item 7 and 13, wherein, at each antenna, the circulator is connected to the input unit over a load-balancing circuit (91).

Item 15. The coverage-enhancing device of item 10 and 13, wherein, at each antenna, the output unit is connected to the circulator over a load-balancing circuit (92).

Item 16. A method for operating a coverage-enhancing device comprising a single antenna array having a plurality of antennas, comprising: receiving an RF signal at said antennas; determining at least one summed signal based on the received RF signals dependent on at least one receive parameter; determining at least one signal output component related to at least one predetermined transmit parameter which is associated with at least one predetermined receive parameter, based on the at least one summed signal; applying said at least one signal output component to a signal output mechanism connected to said plurality of antennas to transmit an RF signal dependent on the at least one predetermined transmit parameter.

Item 17. The method of item 16, wherein determining at least one summed signal comprises determining a first number (KA) of summed signals, each summed signal corresponding to a respective predetermined receive parameter.

Item 18. The method of item 17, wherein determining at least one signal output component comprises determining a second number (KD) of signal output components, each signal output component corresponding to a respective predetermined transmit parameter.

Item 19. The method of item 18, wherein the sum of the first number (KA) and the second number (KD) is at least three.

Item 20. The method of item 19, wherein determining at least one signal output component comprises combining at least two summed signals (SRAI, SRAI) related to different predetermined receive parameters to provide at least one signal output component related to a predetermined transmit parameter associated with the predetermined receive parameters.

Item 21. The method of item 19 or 20, wherein determining at least one signal output component comprises determining at least two signal output components having different predetermined transmit parameter, based on one summed signal (SRAI, SRAI) related to an associated first predetermined receive parameter.

Item 22. The method of any of items 16-21, comprising: obtaining one or more input component signals corresponding to each of at least one predetermined receive parameter by phase rotating and/or amplitude scaling the received signal.

Item 23. The method of item 22, comprising: summing the input component signals corresponding to the same predetermined receive parameter to obtain said at least one summed signal.

Item 24. The method of any of items 16-23, wherein applying said at least one signal output component comprises: splitting the signal output component for obtaining split signal output components for each antenna; combining the split signal output components for each of at least one predetermined transmit parameter at each of the plurality of antennas.

Item 25. The method of any of items 16-24, wherein the receive parameter is indicative of an angle of arrival, AoA, of the received RF signal.

Item 26. The method of any of items 16-25, wherein the transmit parameter is indicative of an angle of departure, AoD, of the transmitted RF signal.

Claims

1. A coverage-enhancing device (20), comprising: a single antenna array (214) having a plurality of antennas (A_m, Ak) configured to receive and transmit radio frequency, RF, signals; and signal processing circuitry (50) comprising: a signal input mechanism (52) configured to provide at least one summed signal (SRI, SRI) based on RF signals received at said plurality of antennas, dependent on at least one receive parameter of the received RF signal; a combinatorial network (53) configured to provide at least one signal output component (STI) related to a predetermined transmit parameter which is associated with a predetermined receive parameter, based on the at least one summed signal (SRI, SRI); a signal output mechanism (54) configured to apply said signal output component to said plurality of antennas, to transmit an output RF signal based on the predetermined transmit parameter.

2. The coverage-enhancing device of claim 1, wherein the signal input mechanism is configured to provide a first number (KA) of summed signals, each summed signal corresponding to a respective predetermined receive parameter.

3. The coverage-enhancing device of claim 2, wherein the combinatorial network is configured to provide a second number (KD) of signal output components, each signal output component corresponding to a respective predetermined transmit parameter.

4. The coverage-enhancing device of claim 3, wherein the sum of the first number (KA) and the second number (KD) is at least three.

5. The coverage-enhancing device of any preceding claim, wherein the combinatorial network (120) comprises a circuit, configured to combine at least two summed signals (SRI, SR2) related to different predetermined receive parameters to provide at least one signal output component (STI) related to a predetermined transmit parameter associated with the predetermined receive parameters.

6. The coverage-enhancing device of any preceding claim, wherein the combinatorial network comprises a circuit, configured to provide at least two signal output components (STI, STI) related to different predetermined transmit parameter configuration, based on a summed signal (SRI) related to an associated first predetermined receive parameter.

7. The coverage-enhancing device of any preceding claim, wherein the signal input mechanism comprises, for each antenna, an input unit (701, 702) configured to phase rotate and/or amplitude scale the received signal to obtain input component signals corresponding to each of at least one predetermined receive parameter.

8. The coverage-enhancing device of claim 7, wherein the input units are connected to a summation unit (711, 712), configured to sum the input component signals corresponding to the same predetermined receive parameter from said antennas.

9. The coverage-enhancing device of any preceding claim, wherein the signal output mechanism (54) is configured to combine the signal output component for each of at least one predetermined transmit parameter at each of the plurality of antennas.

10. The coverage-enhancing device of claim 9, wherein the output mechanism is configured to provide the output component to each of said output units.

11. The coverage-enhancing device of any preceding claim, wherein the receive parameter is indicative of an angle of arrival, AoA, of the received RF signal.

12. The coverage-enhancing device of any preceding claim, wherein the transmit parameter is indicative of an angle of departure, AoD, of the transmitted RF signal.

13. The coverage-enhancing device of any preceding claim, comprising: at each antenna, a circulator (51) connecting the antenna with said input mechanism and said output mechanism.

14. The coverage-enhancing device of claim 7 and 13, wherein, at each antenna, the circulator is connected to the input unit over a load-balancing circuit (91).

15. The coverage-enhancing device of claim 10 and 13, wherein, at each antenna, the output unit is connected to the circulator over a load-balancing circuit (92).

16. A method for operating a coverage-enhancing device comprising a single antenna array having a plurality of antennas, comprising: receiving (1010) an RF signal at said antennas; determining (1020) at least one summed signal based on the received RF signals dependent on at least one receive parameter; determining (1030) at least one signal output component related to at least one predetermined transmit parameter which is associated with at least one predetermined receive parameter, based on the at least one summed signal; applying (1040) said at least one signal output component to a signal output mechanism connected to said plurality of antennas to transmit an RF signal dependent on the at least one predetermined transmit parameter.

17. The method of claim 16, wherein determining at least one summed signal comprises determining a first number (KA) of summed signals, each summed signal corresponding to a respective predetermined receive parameter.

18. The method of claim 17, wherein determining at least one signal output component comprises determining a second number (KD) of signal output components, each signal output component corresponding to a respective predetermined transmit parameter.

19. The method of claim 18, wherein the sum of the first number (KA) and the second number (KD) is at least three.

20. The method of claim 19, wherein determining at least one signal output component comprises combining at least two summed signals (SRAI, SRAI) related to different predetermined receive parameters to provide at least one signal output component related to a predetermined transmit parameter associated with the predetermined receive parameters.

21. The method of claim 19 or 20, wherein determining at least one signal output component comprises determining at least two signal output components having different predetermined transmit parameter, based on one summed signal (SRAI, SRAI) related to an associated first predetermined receive parameter.

22. The method of any of claims 16-21, comprising: obtaining one or more input component signals corresponding to each of at least one predetermined receive parameter by phase rotating and/or amplitude scaling the received signal.

23. The method of claim 22, comprising: summing the input component signals corresponding to the same predetermined receive parameter to obtain said at least one summed signal.

24. The method of any of claims 16-23, wherein applying said at least one signal output component comprises: splitting the signal output component for obtaining split signal output components for each antenna; combining the split signal output components for each of at least one predetermined transmit parameter at each of the plurality of antennas.

25. The method of any of claims 16-24, wherein the receive parameter is indicative of an angle of arrival, AoA, of the received RF signal.

26. The method of any of claims 16-25, wherein the transmit parameter is indicative of an angle of departure, AoD, of the transmitted RF signal.