CN120500815A - On-line inter-array phase offset compensation for a modular coverage enhancement device comprising multiple pairs of antenna arrays - Google Patents

Abstract

Techniques for inter-array phase offset compensation at a modular coverage enhancement device, such as a network controlled repeater (NCR), are disclosed. The modular coverage enhancement device includes a plurality of modules, each module including a plurality of antenna arrays.

Description

On-line inter-array phase offset compensation for a modular coverage enhancement device comprising multiple pairs of antenna arrays

Technical Field

Various embodiments of the present disclosure generally relate to coverage enhancement devices of modular design with multiple pairs of antenna arrays. Various embodiments of the present disclosure relate to coverage enhancement devices that perform inter-array phase offset measurements.

Background

To expand the coverage area of wireless communications, it is contemplated to use Coverage Enhancement Devices (CED), such as Network Control Repeaters (NCR) or Reconfigurable Relay Devices (RRD). RRD is sometimes also referred to as reflective smart surface (RIS) or large smart surface (LIS). See, e.g., Huang,C.,Zappone,A.,Alexandropoulos,G.C.,Debbah,M.,&Yuen,C.(2019).Re-configurable intelligent surfaces for energy efficiency in wireless communication( for reconfigurable intelligent surfaces for energy efficiency enhancement in wireless communications.) IEEE Transactions on Wireless Communications (IEEE wireless communication journal), 18 (8), 4157-4170.CED may also be generally referred to as network enhanced devices because they generally enhance coverage, rank, and/or positioning.

The RRD may not have the ability to provide gain for each antenna, i.e., the antenna is semi-passive and does not amplify the antenna signal. A variable phase shift may be applied to each antenna but a variable amplitude gain may not be applied. Differently, in at least some scenarios, the NCR is configured to apply a variable amplitude gain for each antenna element.

The main difference between RRD and NCR is that in NCR all signals received from the antenna elements of the antenna array are combined at some stage to form a single signal. They are then reassigned to the transmit antenna elements. NCR under the third generation partnership protocol (3 GPP) framework is described, for example, in 3GPP TSG RAN conference #97-eRP-222673 (2022, 9, 12 to 16).

Common between RRD and NCR is that they both use a large antenna array (also called a panel) with antennas and are therefore both configured with spatial filters to apply beamforming. Beamforming requires some algorithm to determine the phase shift value of the antenna and optionally the antenna gain.

In particular, for CED, the input spatial direction (or simply input direction) in which CED accepts an incoming signal on a wireless link and the output spatial direction (or simply output direction) in which CED redirects the incoming signal may be reconfigured by changing the phase relationship (and, where possible, the amplitude relationship) between antennas (and, where applicable, the variable amplitude gain of each antenna). This corresponds to configuring the spatial filter at CED. This corresponds to beamforming. An input beam and an output beam are defined.

Some scenarios are known in which the CED comprises a plurality of pairs of input antenna arrays and output antenna arrays. The input antenna array of each pair is coupled to the output antenna array of the corresponding pair. The pairs of antenna arrays and the coupling between antenna arrays may be referred to as modules. Thus, such a CED may be referred to as a modular CED or a multi-panel CED. Multiple modules facilitate beamforming of a single respective beam.

Disclosure of Invention

Techniques for controlling beamforming in a modular CED are needed.

This need is met by the features of the independent claims. Features of the dependent claims define embodiments.

Hereinafter, techniques are disclosed that facilitate compensating for phase offset between arrays at a modular CED that includes multiple pairs of antenna arrays. The phase offsets between the arrays correspond to different phases of the signals at the respective antenna arrays.

According to various embodiments, the protocol for enabling determination and compensation of inter-array phase offset may be triggered by a control node of the CED, e.g., by a Base Station (BS) of a cellular network.

The protocol may be conditionally triggered according to one or more trigger criteria. Such triggering criteria may include, but are not limited to, one or more communication devices (e.g., BS, terminal, etc.) communicating via the CED being disposed in a near field of the CED, a rank of communication between the communication devices communicating via the CED (the rank corresponding to multiple antenna operation, e.g., multiple input multiple output MIMO operation), and so forth.

According to an embodiment, the control node of the CED triggers a protocol for compensating for the phase offset between the arrays.

According to an embodiment, such triggering of the compensation comprises configuring the CED with a measurement period for measuring the phase offset between the arrays. During these measurement periods, the CED may expect that a particular signal (e.g., a reference signal, also referred to as a pilot signal) will arrive from the associated communication device so that the inter-array phase offset may be measured.

The control node may also trigger communication devices communicating via CED to transmit these signals (e.g., reference signals) during the measurement period.

The first inter-array phase offset may be associated with a first wireless communication device (simply referred to as a communication device) transmitting a first signal to the CED, and the second measurement period may be associated with a second communication device transmitting a second signal to the CED.

According to an embodiment, the CED measures a first inter-array phase offset based on a first signal during a first measurement period, and measures a second inter-array phase offset based on a second signal incident at the CED during a second measurement period.

According to an embodiment, measuring the inter-array phase offset includes measuring phase values of an incident signal at the CED at the plurality of antenna arrays. And the phase value differences correspond to the phase offsets between the arrays.

According to an embodiment, compensating for the inter-array phase offset includes applying a respective phase shift at each antenna array that cancels the inter-array phase offset.

A method of operating a control node of a CED is disclosed. The CED includes multiple pairs of antenna arrays. The first wireless communication device (e.g., a base station or terminal) and the second wireless communication device (e.g., a base station or terminal) communicate via the CED. The method includes obtaining an indication of the capability from the CED. The indication of capability indicates the capability of the CED to measure inter-array phase offset between pairs of antenna arrays. The method also includes configuring a first measurement period for the CED based on the indication. The first measurement period is for measuring a first inter-array phase offset of one or more first signals incident from the first wireless communication device. Further, the method includes configuring a second measurement period for the CED based on the indication. The second measurement period is for measuring a second inter-array phase offset of one or more second signals incident from the second wireless communication device. Further, the method includes triggering the first wireless communication device to transmit one or more first signals during a first measurement period and triggering the second wireless communication device to transmit one or more second signals during a second measurement period.

A computer program includes program code that can be loaded and executed by at least one processor. The at least one processor, when loaded and running the program code, performs such a method as described above.

The control node of the coverage enhancement response device comprises a processor and a memory. The processor is configured to load the program code from the memory and run the program code. The processor, when executing the program code, is configured to obtain from the CED an indication of an ability of the CED to measure inter-array phase offsets between the pairs of antenna arrays. The processor is further configured to configure a first measurement period for the CED based on the indication, the first measurement period for measuring a first inter-array phase offset of one or more first signals incident from the first wireless communication device, and to configure a second measurement period for the CED based further on the indication, the second measurement period for measuring a second inter-array phase offset of one or more second signals incident from the second wireless communication device. The processor is further configured to trigger the first wireless communication device to transmit one or more first signals during a first measurement period and to trigger the second wireless communication device to transmit one or more second signals during a second measurement period.

A method of operating a CED is disclosed. The CED includes multiple pairs of antenna arrays. The first wireless communication device and the second wireless communication device communicate via the CED. The method includes providing an indication of an ability to measure inter-array phase offset between a plurality of pairs of antenna arrays to a control node of the CED.

A computer program includes program code that can be loaded and executed by at least one processor. The at least one processor, when loading and executing the program code, performs such a method as described above.

The CED includes multiple pairs of antenna arrays. The CED further includes a processor and a memory. The processor, when loading and running the program code from the memory, is configured to provide an indication of the ability to measure inter-array phase offset between the pairs of antenna arrays to the control node of the CED.

A method of operating a CED is disclosed. The CED includes multiple pairs of antenna arrays. The first wireless communication device and the second wireless communication device communicate via the CED. The method includes measuring a first inter-array phase offset of one or more first signals incident from a first wireless communication device during a first measurement period. The method also includes measuring a second inter-array phase offset of one or more second signals incident from the second wireless communication device during a second measurement period. The method also includes compensating for the phase offset between the first array and compensating for the phase offset between the second array when the first wireless communication device and the second wireless communication device communicate via the CED.

A computer program includes program code that can be loaded and executed by at least one processor. The at least one processor, when loaded and running the program code, performs such a method as described above.

The CED includes a plurality of pairs of antenna arrays, a processor, and a memory. The processor, when loading the program code from the memory and running the program code, is configured to measure a first inter-array phase offset of the one or more first signals. The one or more first signals are incident from the first wireless communication device during a first measurement period. The at least one processor is further configured to measure a second inter-array phase offset of the one or more second signals. The one or more second signals are incident from the second wireless communication device during a second measurement period. The at least one processor is further configured to compensate for the first inter-array phase offset and the second inter-array phase offset when the first wireless communication device and the second wireless communication device communicate via the CED.

A system includes a CED and a control node of the CED. The system may also include a communication device that communicates via the CED. The control node may be implemented by one of these configuration devices (e.g., by a base station of a cellular network).

It will be understood that the features mentioned above and those yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or alone without departing from the scope of the present disclosure.

Drawings

Fig. 1 schematically illustrates a communication system including a BS, a CED, and a terminal according to various embodiments.

Fig. 2 schematically illustrates details related to control circuitry of the CED, in accordance with various embodiments.

Fig. 3 schematically illustrates aspects related to radio frequency circuitry of a CED, in accordance with various embodiments.

Fig. 4 is a flow chart of a method according to various embodiments.

Fig. 5 is a flow chart of a method according to various embodiments.

Fig. 6 schematically illustrates aspects related to a BS and a terminal of a communication system, in accordance with various embodiments.

Fig. 7 is a signaling diagram.

Detailed Description

Some embodiments of the present disclosure generally provide a plurality of circuits or other electronic devices. All references to circuitry and other electronic devices, and the functionality provided by each, are not intended to be limited to only encompass what is shown and described herein. Although specific indicia may be assigned to the various circuits or other electronic devices disclosed, such indicia are not intended to limit the scope of operation of the circuits and other electronic devices. Such circuits and other electronic devices may be combined with and/or separated from each other in any manner based on the particular type of electrical implementation desired. It should be appreciated that any of the circuits or other electronic devices disclosed herein may include any number of microcontrollers, graphics Processor Units (GPUs), integrated circuits, memory devices (e.g., flash memory, random Access Memory (RAM), read Only Memory (ROM), electrically Programmable Read Only Memory (EPROM), electrically Erasable Programmable Read Only Memory (EEPROM), or other suitable variations of these), and software that cooperate with one another to perform the operations disclosed herein. Additionally, any one or more of the electronic devices can be configured to execute program code embodied in a non-transitory computer readable medium that is programmed to perform any number of functions as disclosed.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be understood that the following description of the embodiments should not be taken in a limiting sense. The scope of the present disclosure is not intended to be limited by the embodiments or figures described below, which are by way of illustration only.

The figures are to be regarded as schematic representations and the elements shown in the figures are not necessarily to scale. Rather, the individual elements are shown so that their function and general purpose will become apparent to those skilled in the art. Any connection or coupling between the functional blocks, devices, components, or other physical or functional units shown in the figures or described herein may also be implemented by indirect connection or coupling. The coupling between the components may also be established through a wireless connection. The functional blocks may be implemented in hardware, firmware, software, or a combination thereof.

Various embodiments of the present disclosure relate to communication between a first communication device and a second communication device. The communication is via CED. For example, the first communication device may be a BS of a cellular network, e.g. according to 3GPP specifications. The second communication device may be a terminal (also referred to as a User Equipment (UE)) wirelessly connected to the BS. Other scenarios are also possible. For example, the first communication device may be an access node of an ad hoc network. CED may also support side-uplink communications. However, hereinafter, for simplicity, a scenario will be disclosed in which a BS of a cellular network communicates with a UE via CED. The techniques disclosed hereinafter may be readily applied to other scenarios.

Various embodiments of the present disclosure relate to CED with a modular design. This means that the CED comprises multiple pairs of antenna arrays. In principle, all antenna arrays observe the same propagation channel towards BS and UE. However, due to the spatial offset of the antenna arrays relative to each other, the observed propagation channels differ in observed phase. The phase difference between these antenna arrays (inter-array phase offset) results in incoherent superposition of the signals emanating from the antenna arrays over the air.

Various embodiments relate to techniques to compensate for phase shifts between arrays. The inter-array phase offset compensation is performed on CED. The BS may assist in inter-array phase offset compensation.

Fig. 1 illustrates an example communication system 100 including a CED 109 and a BS 101 and a UE 102. A beam 679 used by CED 109 to communicate with BS 101 through appropriate beamforming is shown. Also shown is a beam 671 used by CED 109 to communicate with UE 102. One or both of the beams 671,679 may be formed by a plurality of respective antenna arrays/panels at the CED 109 (as will be explained in further detail below).

In general, communications may be in the uplink direction, i.e., from the UE 102 to the BS 101. In this scenario, the UE 102 is a transmitting communication device and the BS 101 is a receiving communication device. In this scenario, beam 671 is an input beam directed along an input direction, and beam 679 is an output beam directed along an output direction.

Downlink communications from BS 101 to UE 102 may also be implemented. In this scenario, BS 101 is a transmitting communication device and UE 102 is a receiving communication device. Beam 679 is an input beam directed along an input direction and beam 671 is an output beam directed along an output direction.

For simplicity, a scenario related to downlink communication will be described hereinafter, however, a similar scenario may also be easily applied to uplink communication from UE 102 to BS 101, or side-link communication between two UEs.

The respective directions of beams 671, 679 (i.e., target input and output directions) may be determined as part of a beam scanning or general beam management procedure using reference techniques available in the art.

A control link 199 between BS 101 and CED 109 is also shown. BS 101 may control CED 109 via control link 199. For example, the BS 101 may provide one or more configuration or control messages to the CED 109, and the CED 109 may provide the configuration or control messages to the BS 101. BS 101 may configure a measurement period that enables CED 109 to measure inter-array phase offset. The CED 109 may report to the BS 101, for example, providing an indication of the inter-array phase offset.

Not all scenarios require the base station 101 to implement the control node of the CED 109. In other scenarios, another node of the cellular network to which BS 101 belongs may implement the control function of CED 109. For example, UE 102 may alternatively or additionally implement control functions of CED 109. Also, dedicated control nodes may be provided.

Fig. 2 schematically illustrates aspects related to CED 109. Processor 1091 and memory 1093 and communication interface 1092 form the control circuitry of CED 109. The CED 109 includes two pairs of antenna arrays 510, 511, 520, 521, each including a plurality of antenna elements 500, which are represented by solid circles in fig. 2 (although fig. 2 illustrates only two pairs of antenna arrays, in general, more than two pairs of antenna arrays may be used). Antenna array 510 and antenna array 520 form a first pair of antenna arrays (represented by dashed lines in fig. 2). Antenna array 511 and antenna array 521 form a second pair of antenna arrays. The antenna array 510 and the antenna array 511 implement an input antenna array, i.e. the phase shift values of the phase shifters associated with the antenna elements 500 (or simply antennas) of the input antenna arrays 510, 511 are determined based on the values of the input directions. These phase shift values are determined to form an input beam 679 (see fig. 1).

The antenna arrays 520, 521 implement output antenna arrays. The phase shift values of the phase shifters (phase shifters not shown in fig. 2) associated with the antenna elements 500 of the output antenna arrays 520, 521 are set to achieve phase shift values that form the output beam 671 (see fig. 1).

The phase shift values of the phase shifters associated with antenna elements 500 may be reconfigured by processor 1091. This is to select the appropriate beam. To this end, the processor 1091 may provide corresponding reconfiguration commands to the antenna arrays 510, 520 via the communication interface 1095. To this end, processor 1091 may load and run program code from memory 1093 and then reconfigure the phase shift values based on the program code. In addition, if each antenna can apply a variable gain, this may be reconfigured by processor 1091.

In general, a pair of antenna arrays 510, 511 may serve a first UE, and a pair of antenna arrays 520, 521 may serve another UE that is located differently from the first UE with respect to CED 109. In such a scenario, different beams may be configured for different pairs of UE-oriented antenna arrays. However, in some scenarios, pairs of antenna arrays 510, 511 and 520, 521 serve the same UE. Here, two UE-oriented antenna arrays form the same beam. Such techniques are discussed herein. In particular, how coherent beamforming is implemented between multiple antenna arrays is discussed. Thus, in general, multiple antenna arrays may work cooperatively to serve a single UE or a single communication device.

Although fig. 2 illustrates control circuitry for controlling the antenna arrays 510, 511, 520, 521, radio Frequency (RF) components and radio frequency coupling between each pair of antenna arrays are not shown. This is shown in fig. 3.

Fig. 3 illustrates aspects related to the RF components of CED 109. Fig. 3 shows a plurality of modules 599 of CED 109 (here 9 modules in total). One of these modules 599 (the module 599 comprising the antenna arrays 510, 520) is shown in more detail, the remaining modules 599 are all configured in a similar manner.

The module 599 (shown in detail in the upper part of fig. 3) comprises an antenna array 510 and an antenna array 520, and a radio frequency coupling 559 arranged between the antenna array 510 and the antenna array 520. Antenna array 510 receives signals, i.e., implements input antenna array 510, and antenna array 520 transmits signals, i.e., implements output antenna array 520.

To enable bi-directional communication, the RF coupling 559 may be replicated or a bi-directional RF component may be implemented. The different modules may be dedicated to uplink or downlink communications. This allocation of modules to uplink or downlink communications, respectively, is reconfigurable. For example, the BS 101 or another control node of the CED 109 may reconfigure the CED 109 to assign a particular module to uplink or downlink communications, respectively.

Each antenna element 500 is associated with a respective phase shifter 561, 562, 563, which applies a respective phase shift value (denoted α). This defines a beamformer, i.e. an input beam 679. The phase shifter signals are then combined at a combining node 552 (which corresponds to the NCR implementation of CED 109), and then a fixed gain amplifier 551 (typically optional) is provided. The amplified signal is then split at node 553 and forwarded to phase shifters 571, 572, 573 associated with antenna elements 500 of output antenna array 520. This defines the beamformer of the output antenna array 520, i.e., the output beam 671.

A global phase shifter 591 is also shown disposed between the combining node 552 and the splitting node 553. The global phase shifter 591 is used in some scenarios to compensate for inter-array phase shifts, as will be explained in further detail below. Alternatively, antenna specific phase shifters 561-563, 571-573 may also be used to compensate for inter-array phase offsets.

Next, details concerning the phase shift between arrays will be explained. Consider two modules 599 (both configured for DL communications) and assume that they are equipped with the same beamforming pair (i.e., the same input beam and output beam), one directed to BS 101 and one directed to UE 102.

The complex baseband of the signal received at UE 102 is denoted s (t) +exp (iα) s (t). The variable α represents the phase difference between the end-to-end signal paths via the two modules, i.e., α is the inter-array phase offset between the two modules. The value of α depends on the placement of BS 101 and UE 102 relative to the respective antenna arrays of the two modules.

The intention is to force the adjustment of α≡0 so that the signal to noise ratio at the UE 102 is maximized. This corresponds to compensation of phase offset between arrays. Various techniques may be used to compensate for the phase offset between the arrays. In a first embodiment, factory/pre-compensation of phase offset between arrays is applied. Alternatively or additionally, an on-line compensation of the inter-array phase offset is applied, i.e. during operation of the CED 109, wherein the position variations of the BS 101 and the UE 102 are taken into account.

Various techniques are based on the discovery that pre-compensation of inter-array phase offsets is difficult to achieve when BS 101 and/or UE 102 are in the near field of CED 109. In particular, for such a scenario, it is desirable to perform online compensation. This finding is explained in detail below.

The inter-array phase offset α is due to the angle between CED and UE and BS (rather than the angle at which the beam is directed, e.g., the maximum of the beam profile).

For factory/pre-compensation of inter-array phase offset, the beam applied to each module is phase adjusted so that α≡0 at the time of manufacture/final calibration. This applies if the beams do point exactly to BS 101 and UE 102, respectively. This means that during operation, if the same beam is applied to two different modules, it is intended to apply a beam pair that is inter-array phase offset compensated using factory compensation. If such factory compensation is done, any α+.0 comes from the beam not pointing exactly to the BS 101 and UE 102, respectively. For illustration, referring to fig. 1, a scenario is disclosed in which beam 671 is used to serve user device 102, however, the maximum value of the beam profile (represented by the solid line in fig. 1) is slightly offset from the actual direction of user device 102 (represented by the dashed line in fig. 1). In short, the beam 671 is not directed directly to the UE 102.

Suppose now that BS 101 and UE 102 are in the far field of CED 109. Then, if factory compensation is done, we can assume that the beam is reasonably directed to BS 101 and UE 102, which means that α is small. Perhaps so small that no further compensation is required. The exception is when a wide beam is used. The important point is then that the device is not well positioned by the system in the angular domain, so that the value of the factory compensation may be far from the true value. But in general, factory calibration can be considered quite effective when far field assumptions are true.

It is now assumed that BS 101 and/or UE 102 are (in the near field of) CED 109, then factory/pre-calibration becomes significantly more challenging or even impossible to achieve if the beams applied at the modules are directed to the same far field angle, factory calibration is not possible because the value α depends on the distance between CED and BS 101 and UE 102, respectively.

Specifically, in the near field, the angle from the CED 109 to the UE 102 (or, as such, to the BS 101) is different for each antenna array of the plurality of modules of the CED. In other words, the spatial output direction for beamforming is different between antenna arrays.

If the modules use different beams, a degree of factory/pre-calibration may be performed. By the fact that the two beams are pointing in different directions, the assumed positions of the UE and BS can be estimated and then factory calibration can be performed. However, this results in a much larger value for α than in the far field case.

All this means that there are some cases where the modular CED is not phase coherent in design, but on-line inter-array phase offset compensation according to the present disclosure is helpful.

To achieve inter-array phase compensation during operation of the CED 109, the CED 109 includes a measurement unit 595 for each module. Using the measurement unit 595, the signal phase downstream of the combining node 552 of the coupling 559 and upstream of the splitting node 553 (e.g., upstream of the amplifier 551 and the global phase shifter 591) can be measured. Thus, the phase value of each module can be measured.

The measurement unit 595 observes a time-continuous RF signal. The measurement unit 595 measures an average phase of a baseband signal included in the RF signal for a certain period of time. The measurement units 595 of the plurality of modules 599 of the CED 109 may measure phases coherently, i.e. with respect to the same reference.

In general, there are a variety of options for implementing the measurement element 595. For example, each module may include corresponding receiver circuitry forming a corresponding measurement element 595. In other scenarios, signals from two different modules may be compared to measure phase offset. Here, a combination of a signal combiner and a power detector may be used. The specific hardware implementation of the measurement unit 595 is not related to the techniques disclosed herein and may depend on various hardware implementations according to the reference implementation.

In some hardware implementations, it may be desirable to calibrate multiple measurement modules 595 of different modules so that the phases relative to the same reference are measured.

Furthermore, although in the scenario of fig. 3 the measurement unit 595 is located upstream of the amplifier 551 (close to the input antenna array 510), in other scenarios the measurement unit 595 may also be located downstream of the amplifier 551, even downstream of the phase shifter 591.

The measurement unit 595 of CED 109 supports the following protocol for online compensation of phase offset between arrays. Such protocols will be described in further detail in connection with subsequent figures.

Fig. 4 is a flow chart of a method according to various embodiments. Fig. 4 illustrates a method for operating a control node of CED. The control node may be implemented by a BS of a cellular network. The method of fig. 4 is used in a control node.

The method of fig. 4 involves implementing on-line compensation of phase offset between arrays of modular CED (such as CED 109 discussed above in connection with fig. 1, 2, and 3).

The optional boxes are indicated by dashed lines.

At block 3005, the CED is configured to serve the first communication device and the second communication device. This may also be preconfigured.

For simplicity, hereinafter, it is assumed that CED is configured to serve BSs and UEs, such as BS 101 and UE 102, as described above. The CED is configured to apply corresponding beams, such as beams 679 and 671 discussed above in connection with fig. 1.

Next, at block 3010, the control node obtains from the CED an indication of the CED's ability to measure inter-array phase offsets between pairs of antenna arrays. The capability message at block 3010 is typically optional. The control node may also know or assume this capability in advance.

Then, at block 3015, the control node triggers a protocol for measuring and compensating for phase offsets between the arrays. Since this is done at deployment of the CED, it may be referred to as online compensation.

In some scenarios, on-line compensation of inter-array phase offset may be conditionally performed at block 3015. That is, the protocol will only be triggered in response to a particular situation (one or more trigger criteria). For example, one trigger condition may be detection that the UE and/or BS is in the near field of CED. Then, online compensation of the inter-array phase offset may be conditionally performed in response to detecting that the BS and/or UE are in the near field. Another example trigger condition is whether the rank of communication between the UE and the BS meets a criterion, e.g., is greater than 2. For example, it may be checked whether different modules of the modular CED cooperate to service a communication device using a single data stream. Here, low rank communication (single data stream) is used for multiple modules. In other scenarios using multiple-input multiple-output (MIMO) technology, using spatial diversity, multiple data streams may be used to achieve higher throughput and/or higher reliability. In this scenario, since different antenna arrays forward different data streams, on-line compensation of the inter-array phase offset may not be required.

In order to detect whether the BS and/or UE is in the near field of CED, a positioning technique may be employed. For example, reference positioning techniques are available in the 3GPP framework. Satellite positioning or multi-angle measurements using cellular signals may be employed. Based on such positioning techniques, a distance between the CED and the BS and/or UE may be determined. The distance may be compared to a threshold that defines whether the BS and/or UE is located in the near field of the CED.

Block 3015 may include indicating to CED that on-line compensation of inter-array phase offset should be performed.

Block 3015 may include configuring a first measurement period for the CED to measure a first inter-array phase offset of a first signal incident from the BS, and configuring a second measurement period for the CED to measure a second inter-array phase offset of a second signal incident from the UE.

Block 3015 may include triggering the BS to transmit a first reference signal during a first measurement period. For example, in the case of a separate control node involving CED, this may include providing a corresponding control message to the BS. In case the BS itself implements the control node of the CED, this may comprise providing the respective command to the associated layer of the transport protocol stack of the BS. Accordingly, triggered by block 3015, the BS transmits a first reference signal to the CED during the first measurement period. During the first measurement period, typically all modules of the CED are configured for downlink using the preconfigured beam directed to the BS of block 3005. The CED uses the corresponding measurement unit (see fig. 3: measurement unit 595) to perform the phase measurement and records the corresponding phase value per module. The recorded phase value is denoted by θ _1,m, where m refers to the module index. This corresponds to detecting the inter-array phase offset of the BS-facing antenna array.

Block 3015 may include triggering the UE to transmit a second signal during a second measurement period. This may include, for example, a corresponding control message provided to the UE, e.g., a Radio Resource Control (RRC) control message. During the second measurement period, typically all modules of the CED are configured for uplink. A phase measurement is recorded for each module of CED. These are denoted by θ _2,m, where m refers to the module index. The phase value is measured using the beam directed to the UE previously configured in block 3005. This corresponds to detecting inter-array phase offset of the UE-oriented antenna array.

These measurements triggered by block 3015 enable the CED to measure inter-array phase offsets. Such measurements are based on reference phases, which may generally be arbitrarily selected or one module may be designated as a reference module, e.g. module m=1. The phase offset between each array (for all modules m) is given by θ _1,1-θ_1,m+θ_2,1-θ_2,m.

In some embodiments, the CED reports to the BS the inter-array phase offset determined for each array. At block 3020, the BS may obtain an indication of the corresponding inter-array phase offset from the CED.

Then, at block 3025, normal communications may begin. Here, typically, some modules are configured as UL and some modules are configured as DL and begin normal operation, applying compensation for inter-array phase offset, e.g., using global phase shifters available in each module. As a result, for example in DL, all signals arrive at the UE 102 in phase.

Fig. 5 is a flow chart of a method according to various embodiments. The method of fig. 5 is used in CED. The method of fig. 5 involves operating CED.

The method of fig. 5 is to compensate for the inter-array phase offset at CED. Thus, the method of fig. 5 is interrelated with the method of fig. 4 in that it is associated with a cooperation between the operation of the CED and the operation of the BS/control node performing the method of fig. 4.

At block 3105, the CED services the first communication device and the second communication device. In other words, the first communication device and the second communication device communicate via the CED. For illustrative purposes, it is assumed that the first communication device and the second communication device are a BS and a UE.

As explained above in connection with block 3005 in fig. 4, the control node may configure the CED service first communication device and the second communication device. The corresponding configuration message may be obtained at the CED via a control link (see fig. 2: control link 199).

At optional block 3110, the CED provides an indication of its ability to measure inter-array phase offset between pairs of antenna arrays to a control node of the CED. The CED may provide the corresponding control message via a control link (see fig. 2: control link 199).

Block 3110 corresponds to and is interrelated with block 3010 of fig. 4.

Next, at block 3115, inter-array phase offset measurements are performed. This includes configuring, by a control node of the CED, a first measurement period, and configuring, by the control node, a second measurement period. As an alternative to this configuration of the first and second measurement periods, the first and second measurement periods may also be fixedly preconfigured. For example, they may be preconfigured according to a repeating schedule.

Further, block 3115 includes measuring a first inter-array phase offset of a first reference signal incident from the BS during a first measurement period, and measuring a second inter-array phase offset of a second signal incident from the UE during a second measurement period. These measurements are performed using previously determined beams for serving the BS and UE, respectively, and such beams may be configured in block 3105.

Alternatively, the variable gain amplifier of the CED may be switched to the idle mode during the measurement period. This will enable noise in the measurement to be reduced.

Then, after performing the inter-array phase offset measurement, the method begins at block 3120. Here, optionally, an indication of the inter-array phase offset may be provided to the BS. Corresponding techniques have been previously discussed in connection with block 3020 of fig. 4.

Next, at block 3125, communication between the BS and the UE is started. This includes activating respective beams directed to the BS and UE, respectively. In addition, compensating for the phase offset between the first arrays proceeds and compensating for the phase offset between the second arrays. This includes using the global phase shifter of each module to apply the corresponding inter-array phase offset.

Fig. 6 schematically shows aspects of a combined communication system 100 (see fig. 1). Fig. 6 schematically shows details related to the UE 102 and the BS 101.

BS 101 comprises a processor 1011 which can load program code from memory 1015 and run the program code. Execution of the program code may cause the processor 1011 to perform the techniques described herein, e.g., configuring the CED 109, e.g., performing compensation for inter-array phase offset, transmitting a signal, e.g., a reference signal (having a predetermined signal amplitude and shape), directing the signal to the CED 109 using beamforming, performing the method of fig. 4, etc.

Fig. 6 illustrates aspects related to UE 102. UE 102 includes a processor 1021 and a memory 1025. Processor 1021 may load program code from memory 1025 and execute the program code. When executing program code, the processor can perform techniques as disclosed herein, such as receiving or transmitting signals via a wireless communication interface 1022 that accesses one or more antennas 1024, transmitting signals (e.g., reference signals) to the CED 109, etc.

Fig. 7 is a signaling diagram of communication between BS 101 and UE 102 and CED 109. Communication using the dashed line is via control link 199. The communication on the carrier of the cellular network to which the base station 101 belongs is indicated by a solid line.

The signaling of fig. 7 may be used to implement the methods of fig. 4 and 5.

In the scenario of fig. 7, BS 101 acts as a control node for CED 109. In other embodiments, another node may be used as a control node. In this case, the communication indicated by the dashed line will be performed between the CED 109 and the other control nodes.

At 905, BS 101 provides configuration message 4005 to CED 109 to configure the beams directed to BS 101 and UE 102 for CED 109 to use for communication over the carriers of the cellular network. For example, a beam 679 directed to BS 101 and a beam 671 directed to UE 102 may be configured (see fig. 1).

Accordingly, 905 implements blocks 3005 and 3105 of the methods of fig. 4 and 5, respectively.

Alternatively, the CED 109 may provide its ability to make phase measurements using the corresponding control message 4006 at 906.

At 910, BS 101 provides a configuration message to CED 109 to configure measurement periods 981, 982 for CED 109.

Then, during a measurement period 981, BS 101 transmits one or more reference signals 4020 to CED 109 at 920 (e.g., using an appropriate beam directed to CED 109). CED 109 activates the beam configured using configuration message 4005 at 905.

During measurement period 982, UE 102 transmits one or more reference signals 4021 to CED 109 at 925. For this purpose, the measurement period 982 is configured accordingly for the UE 102 using the configuration message 4015 sent by the BS 101 at 915. UE 102 uses a beam directed to CED 109. During measurement period 982, CED 109 activates a beam directed to UE 102, which is configured using configuration message 4005 at 905.

Thus, 910, 915, 920, and 925 implement blocks 3015 and 3115, respectively, of the methods according to fig. 4 and 5. This implements blocks 3020 and 3120 of the methods of fig. 4 and 5, respectively.

Alternatively, CED 109 may report the inter-array phase offset using a corresponding control message 4024 at 926.

Communication between BS 101 and UE 102 (downlink communication is shown in fig. 7, but uplink communication is equally possible) is then initiated at block 930, where payload data 4025 is transmitted. The communication is via CED 109. CED applies compensation of the inter-array phase offset based on the respective phase measurements implemented based on reference signals 4020 and 4021. The beam configured at 905 is activated. This implements blocks 3025 and 3125 of the methods of fig. 4 and 5, respectively.

In summary, techniques have been disclosed that help compensate for phase shifts between arrays at CED, which includes multiple pairs of antenna arrays. These multiple pairs of antenna arrays cooperate to serve a single communication device, such as a UE or a base station. The corresponding modular CED has been described.

The various techniques disclosed are based on the discovery that inter-array phase shifts are based on, firstly, array geometry and, secondly, input and output spatial directions. Since the beams are configured and the array geometry is known, no calibration signaling is required on the surface. However, the real-space direction of the communication device may be different from the beam configuration, i.e. the direction of the maximum of the beam profile may be different from the actual direction in which the communication device is located. Phase correction may be applied to compensate for the corresponding inter-array phase offset. Capability signaling is disclosed, for example, to ensure that the CED is able to perform self-calibration of such inter-array phase offsets.

In summary, the following examples are specifically disclosed.

Embodiment 1. A method of operating a control node (101) of a coverage enhancement device (109), the coverage enhancement device comprising a plurality of pairs of antenna arrays (510, 511, 520, 521), a first wireless communication device (101, 102) and a second wireless communication device (101, 102) communicating via the coverage enhancement device (109),

Wherein the method comprises the following steps:

acquiring (3010) from the coverage enhancement device (109) an indication of a capability to measure inter-array phase offset between the pairs of antenna arrays (510, 511, 520, 521),

Configuring (3015) for the coverage enhancement device (109) a first measurement period (981, 982) for measuring a first inter-array phase offset of one or more first signals (4020, 4021) incident from the first wireless communication device (101, 102) based on the indication,

Configuring (3015) a second measurement period (981, 982) for the coverage enhancement device (109) based on the indication, the second measurement period being for measuring a second inter-array phase offset of one or more second signals (4020, 4021) incident from the second wireless communication device (101, 102),

-Triggering (3015) the first wireless communication device (101, 102) to transmit one or more first signals (4020, 4021) during a first measurement period (981, 982), and

-Triggering (3015) the second wireless communication device (101, 102) to transmit one or more second signals (4020, 4021) during a second measurement period (981, 982).

Embodiment 2. The method according to embodiment 1, further comprising:

an indication of the first inter-array phase offset and the second inter-array phase offset is obtained (3020) from a coverage enhancement device (109).

Embodiment 3. The method according to embodiment 1 or 2, further comprising:

Configuring (3005) the coverage enhancement device (109) to serve the first wireless communication device (101, 102) using a first beam (671, 679) and to serve the second wireless communication device (101, 102) using a second beam (671, 679),

-Configuring the coverage enhancement device (109) to measure the first inter-array phase offset using the first beam (671, 679), and

-Configuring the coverage enhancement device (109) to measure the second inter-array phase offset using the second beam (671, 679).

Embodiment 4. The method of any of the preceding embodiments, further comprising:

detecting that at least one of the first wireless communication device (101, 102) or the second wireless communication device (101, 102) is in the near field of the coverage enhancement device (109),

Wherein the first measurement period (981, 982) and the second measurement period (981, 982) are selectively configured in a near field of the coverage enhancement device (109) in response to detecting that at least one of the first wireless communication device (101, 102) and the second wireless communication device (101, 102).

Embodiment 5. A method of operating a coverage enhancement device (109) comprising a plurality of pairs of antenna arrays (510, 511, 520, 521), a first wireless communication device (101, 102) and a second wireless communication device (101, 102) communicating via the coverage enhancement device (109),

Wherein the method comprises the following steps:

-providing an indication of a capability to the control node (101) of the coverage enhancement device (109), the capability being used to measure inter-array phase offset between pairs of antenna arrays (510, 511, 520, 521).

Embodiment 6. A method of operating a coverage enhancement device (109) comprising a plurality of pairs of antenna arrays (510, 511, 520, 521), a first wireless communication device (101, 102) and a second wireless communication device (101, 102) communicating via the coverage enhancement device (109),

Wherein the method comprises the following steps:

Measuring (3115) a first inter-array phase offset of one or more first signals (4020, 4021) incident from the first wireless communication device (101, 102) during a first measurement period (981, 982),

-Measuring (3115) a second inter-array phase offset of one or more second signals (4020, 4021) incident from the second wireless communication device (101, 102) during a second measurement period (981, 982), and

-Compensating (3125) for the first inter-array phase offset and compensating for the second inter-array phase offset when the first wireless communication device (101, 102) and the second wireless communication device (101, 102) communicate via the coverage enhancement device (109).

Embodiment 7. The method of embodiment 6 further comprising:

configuring a first measurement period (981, 982) by a control node (101) of a coverage enhancement device (109),

-Configuring, by the control node (101) of the coverage enhancement device (109), a second measurement period (981, 982).

Embodiment 8. The method of embodiment 6 or 7, further comprising:

-switching the one or more variable gain amplifiers to idle mode during a first measurement period (981, 982) and a second measurement period (981, 982).

Although the disclosure has been shown and described with respect to certain preferred embodiments, equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification. The present disclosure includes all such equivalents and modifications, and is limited only by the scope of the following claims.

For illustration, various techniques have been disclosed in which the inter-array phase offset is compensated using a global phase shifter (see fig. 3: global phase shifter 591) that applies a phase shift equally to all antennas of an antenna array. Alternatively or additionally, the inter-array phase offset may also be compensated at least in part by antenna specific phase shifters (see fig. 3: phase shifters 561, 562, 563, 571, 572, 573), where the inter-array phase offset may be used as references for the respective antenna specific phase shifters and phase shift values associated with beamforming may be applied over these references.

For further explanation, various embodiments have been disclosed in connection with the scenario in which a BS transmits downlink data to a UE via CED. Similar techniques may be readily applied to uplink communications, side-uplink communications, or other communications scenarios.

Claims (16)

1. A method of operating a control node (101) of a CED (109), wherein the CED comprises a plurality of pairs of antenna arrays (510, 511, 520, 521), a first wireless communication device (101, 102) and a second wireless communication device (101, 102) communicate via the CED (109), The method comprises: - obtaining (3010) from the CED (109) an indication of a capability to measure inter-array phase offsets between the plurality of pairs of antenna arrays (510, 511, 520, 521), - configuring (3015) a first measurement period (981, 982) for the CED (109) based on the indication, the first measurement period being used to measure a first inter-array phase offset of one or more first signals (4020, 4021) incident from the first wireless communication device (101, 102), - configuring (3015) a second measurement period (981, 982) for the CED (109) based on the indication, the second measurement period being used to measure a second inter-array phase offset of one or more second signals (4020, 4021) incident from the second wireless communication device (101, 102), - triggering (3015) the first wireless communication device (101, 102) to transmit the one or more first signals (4020, 4021) during the first measurement period (981, 982), and - triggering (3015) the second wireless communication device (101, 102) to transmit the one or more second signals (4020, 4021) during the second measurement period (981, 982). 2. The method according to claim 1, further comprising: - obtaining (3020) from the CED (109) an indication of the first inter-array phase offset and the second inter-array phase offset. 3. The method according to claim 1 or 2, further comprising: - configuring (3005) the CED (109) to serve the first wireless communication device (101, 102) using a first beam (671, 679) and to serve the second wireless communication device (101, 102) using a second beam (671, 679), - configuring the CED (109) to measure the first inter-array phase offset using the first beam (671, 679), and - configuring the CED (109) to measure the second inter-array phase offset using the second beam (671, 679). 4. The method according to any one of the preceding claims, further comprising: - detecting that at least one of the first wireless communication device (101, 102) and the second wireless communication device (101, 102) is in the near field of the CED (109), wherein the first measurement period (981, 982) and the second measurement period (981, 982) are selectively configured in response to detecting that at least one of the first wireless communication device (101, 102) or the second wireless communication device (101, 102) is in the near field of the CED (109). 5. A method of operating a CED (109), the CED comprising a plurality of pairs of antenna arrays (510, 511, 520, 521), a first wireless communication device (101, 102) and a second wireless communication device (101, 102) communicating via the CED (109), The method comprises: - providing an indication to a control node (101) of the CED (109) of a capability to measure inter-array phase offsets between the plurality of pairs of antenna arrays (510, 511, 520, 521). 6. A method of operating a CED (109), the CED comprising a plurality of pairs of antenna arrays (510, 511, 520, 521), a first wireless communication device (101, 102) and a second wireless communication device (101, 102) communicating via the CED (109), The method comprises: - measuring (3115) a first inter-array phase offset of one or more first signals (4020, 4021) incident from said first wireless communication device (101, 102) during a first measurement period (981, 982), - measuring (3115) a second inter-array phase offset of one or more second signals (4020, 4021) incident from the second wireless communication device (101, 102) during a second measurement period (981, 982), and - When the first wireless communication device (101, 102) and the second wireless communication device (101, 102) communicate via the CED (109), compensating (3125) the first inter-array phase offset and compensating the second inter-array phase offset. 7. The method according to claim 6, further comprising: - configuring the first measurement period (981, 982) by a control node (101) of the CED (109), - configuring the second measurement period (981, 982) by a control node (101) of the CED (109). 8. The method according to claim 6 or 7, further comprising: - In the first measurement period (981, 982) and the second measurement period (981, 982) during which one or more variable gain amplifiers are switched to idle mode. 9. A control node (101) of a CED (109), the control node comprising a processor and a memory, the processor being configured to load a program code from the memory and execute the program code, the processor being configured to: - obtaining (3010) from the CED (109) an indication of a capability to measure inter-array phase offsets between a plurality of pairs of antenna arrays (510, 511, 520, 521), - configuring (3015) a first measurement period (981, 982) for the CED (109) based on the indication, the first measurement period being used to measure a first inter-array phase offset of one or more first signals (4020, 4021) incident from a first wireless communication device (101, 102), - configuring (3015) a second measurement period (981, 982) for the CED (109) based on the indication, the second measurement period being used to measure a second inter-array phase offset of one or more second signals (4020, 4021) incident from a second wireless communication device (101, 102), - triggering (3015) the first wireless communication device (101, 102) to transmit the one or more first signals (4020, 4021), and - triggering (3015) the second wireless communication device (101, 102) to transmit the one or more second signals (4020, 4021) during the second measurement period (981, 982). 10. The control node according to claim 9, wherein the processor is configured to perform the method according to claim 1. 11. A CED (109), comprising a plurality of pairs of antenna arrays (510, 511, 520, 521), a processor and a memory, wherein the processor is configured to: - providing an indication to a control node (101) of the CED (109) of a capability to measure inter-array phase offsets between the plurality of pairs of antenna arrays (510, 511, 520, 521). 12. The CED according to claim 11, Wherein, the processor is configured to execute the method according to claim 5. 13. A CED (109), comprising a plurality of pairs of antenna arrays (510, 511, 520, 521), a processor and a memory, wherein the processor is configured to: - measuring (3115) a first inter-array phase offset of one or more first signals (4020, 4021) incident from a first wireless communication device (101, 102) during a first measurement period (981, 982), - measuring (3115) a second inter-array phase offset of one or more second signals (4020, 4021) incident from a second wireless communication device (101, 102) during a second measurement period (981, 982), and - When the first wireless communication device (101, 102) and the second wireless communication device (101, 102) communicate via the CED (109), compensating (3125) the first inter-array phase offset and compensating the second inter-array phase offset. 14. The CED according to claim 13, Wherein, the processor is configured to execute the method according to claim 6. 15. A system comprising the control node according to claim 9 and the CED according to claim 11 or 13. 16. The system of claim 15, further comprising a first communication device and a second communication device.