EP3753123A1

EP3753123A1 - Method, system and apparatus to provide individual antenna configuration selections within a mimo antenna array

Info

Publication number: EP3753123A1
Application number: EP18705635.3A
Authority: EP
Inventors: Hardy Halbauer; Dirk Wiegner; Andreas Weber; Thorsten Wild
Original assignee: Nokia Solutions and Networks Oy
Current assignee: Nokia Solutions and Networks Oy
Priority date: 2018-02-15
Filing date: 2018-02-15
Publication date: 2020-12-23
Also published as: WO2019158207A1; CN112005503A; CN112005503B

Abstract

An apparatus comprising at least one processor and at least one memory including computer code for one or more programs. The at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to determine at least one dynamic transmission parameter, provide an individual transmitter antenna configuration selection within a multiple-input multiple-output antenna array based on the at least one dynamic transmission parameter and implement the individual antenna configuration selection within a multiple-input multiple-output antenna array by control of at least one power amplifier and/or at least one power divider located before each antenna element.

Description

Title METHOD, SYSTEM AND APPARATUS TO PROVIDE INDIVIDUAL ANTENNA

CONFIGURATION SELECTIONS WITHIN A MIMO ANTENNA ARRAY

Field

The present application relates to a method, apparatus, system and computer program and in particular but not exclusively to a method and apparatus for a 5G New Radio communications network.

Background

A communication system can be seen as a facility that enables communication sessions between two or more entities such as user terminals, base stations/access points and/or other nodes by providing carriers between the various entities involved in the communications path. A communication system can be provided for example by means of a communication network and one or more compatible communication devices. The communication sessions may comprise, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and/or content data and so on. Non-limiting examples of services provided comprise two-way or multi-way calls, data communication or multimedia services and access to a data network system, such as the Internet.

In a wireless communication system at least a part of a communication session between at least two stations occurs over a wireless link.

A user can access the communication system by means of an appropriate communication device or terminal. A communication device of a user is often referred to as user equipment (UE). A communication device is provided with an appropriate signal receiving and transmitting apparatus for enabling communications, for example enabling access to a communication network or communications directly with other users. The communication device may access a carrier provided by a station or access point, and transmit and/or receive communications on the carrier. The communication system and associated devices typically operate in accordance with a given standard or specification which sets out what the various entities associated with the system are permitted to do and how that should be achieved. Communication protocols and/or parameters which shall be used for the connection are also typically defined. One example of a communications system is Universal Terrestrial Radio Access Network (UTRAN) (3G radio), long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS), and now 5G New Radio (NR) radio-access technology. 5G NR is being standardized by the 3rd Generation Partnership Project (3GPP).

One of the aspects of 5G New Radio (NR) is that base stations will have to support larger bandwidths than today’s LTE base stations. In addition, they will have to support also massive multiple-input multiple-output (MIMO) techniques for increased spectral efficiency and the capability to serve many users simultaneously with high data rates. Therefore, future base stations will be equipped with large antenna arrays with a high number of antenna elements.

Summary

According to an aspect, there is provided an apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to: determine at least one dynamic transmission parameter; provide an individual transmitter antenna configuration selection within a multiple-input multiple-output antenna array based on the at least one dynamic transmission parameter; and implement the individual antenna configuration selection within a multiple-input multiple-output antenna array by control of at least one power amplifier and/or at least one power divider located before each antenna element.

The apparatus caused to determine at least one dynamic transmission parameter may be caused to determine at least one of: a number of user equipment the apparatus is in communication with; a user demand parameter; locations of user equipment the apparatus is in communication with; a defined transmission power; an average transmitted power in one direction during a specified time interval; a time; a date; and a mode of operation defining in which massive multiple-input multiple-output mode the apparatus is operating.

The apparatus caused to provide an individual transmitter antenna configuration selection within a multiple-input multiple-output antenna array based on the at least one dynamic transmission parameter may be caused to perform at least one of: provide individual transmitter antenna configuration selections within a multiple-input multiple-output antenna array on an antenna element by element basis within an antenna sub-panel; provide individual transmitter antenna configuration selections within a multiple-input multiple-output antenna array on an antenna subpanel by sub-panel basis; provide individual transmitter antenna configuration selections within a multiple-input multiple-output antenna array on an antenna element polarisation by antenna element polarisation basis.

The apparatus caused to implement the individual antenna configuration selection within a multiple-input multiple-output antenna array by control of at least one power amplifiers and/or at least one power divider located before each antenna element may be caused to perform at least one of: control at least one switch coupling a power input for the at least one power amplifier to a power supply unit; control at least one power supply unit coupled to at least one power amplifier; control the at least one power divider configured to selectively couple an output from the at least one power amplifier to antenna elements; and control at least one power divider of the at least one power dividers configured to selectively couple an output from the at least one power amplifier to at least one further power divider of the at least one power divider and control the at least one further power divider configured to selectively couple the output from the at least one power amplifier to the antenna elements.

The apparatus caused to provide an individual transmitter antenna configuration selection within a multiple-input multiple-output antenna array based on the at least one dynamic transmission parameter may be caused to: measure a channel between the apparatus and at least one further apparatus based on at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array; determine at least one performance parameter associated with the measured channel for the at least two candidate individual transmitter antenna configurations; select one of the at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array based on the at least one performance parameter; and check whether the selected one of the at least two candidate individual transmitter antenna configurations meet or exceed a determined performance requirement.

The apparatus caused to measure a channel between the apparatus and at least one further apparatus based on at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array may be caused to perform at least one of: measure uplink sounding in a full digital array time division duplex apparatus; measure downlink reference signal and channel state indication feedback in a full digital array frequency division duplex apparatus; measure downlink reference signal and channel state indication feedback in a full digital array time division duplex apparatus; measure uplink sounding for different sub-panel configurations in a hybrid array time division duplex apparatus; measure downlink reference signal and channel state indication feedback for different sub-panel configurations in a hybrid array frequency division duplex apparatus; and measure downlink reference signal and channel state indication feedback for different sub-panel configurations in a hybrid array time division duplex apparatus.

The apparatus may be further caused to: measure a channel between the apparatus and at least one further apparatus based on the at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array; calculate downlink channel covariance matrices out of estimated downlink channel matrices; and wherein the apparatus caused to select one of the at least two candidate individual transmitter antenna configurations within the multiple- input multiple-output antenna array based on the at least one performance parameter may be caused to perform at least one of: select highly correlated antenna elements to be switched off; select antenna elements based on an angular spread deduced in one or more different geometrical dimensions, the deduced angular spread defining one or more dimensions along which a number of antenna elements to be switched off is selected; and select antenna elements based on a spatial covariance/correlation of antenna elements in a separate horizontal and vertical directions.

The apparatus caused to provide an individual transmitter antenna configuration selection within a multiple-input multiple-output antenna array based on the at least one dynamic transmission parameter may be caused to optimize a function of weighted sum of the at least one dynamic transmission parameter and a total required power consumption and determine at least one dynamic transmission parameter based on a selection of a set of the further apparatus out of the set of all active further apparatus and a selection of a set of antenna elements out of the set of all antenna elements within the multiple-input multiple-output antenna array.

The apparatus caused to measure a channel between the apparatus and at least one further apparatus based on at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array may be caused to measure a uplink channel between the apparatus and at least one further apparatus using all antenna elements within the multiple-input multiple-output antenna array as receiver antennas, and wherein the apparatus caused to select one of the at least two configurations within the multiple input multiple output antenna array based on the at least one performance parameter may be caused to calculate one or more downlink candidate individual transmitter antenna configuration selections based on the measured uplink channel.

According to a second aspect there is provided a method comprising: determining at least one dynamic transmission parameter; providing an individual transmitter antenna configuration selection within a multiple-input multiple-output antenna array associated with an apparatus based on the at least one dynamic transmission parameter; and implementing the individual antenna configuration selection within a multiple-input multiple-output antenna array by control of at least one power amplifier and/or at least one power divider located before each antenna element.

Determining at least one dynamic transmission parameter may comprise at least one of: a number of user equipment the apparatus is in communication with; a user demand parameter; locations of user equipment the apparatus is in communication with a defined transmission power; an average transmitted power in one direction during a specified time interval; a time; a date; and a mode of operation defining in which massive multiple-input multiple-output mode the apparatus is operating.

Providing an individual transmitter antenna configuration selection within a multiple-input multiple-output antenna array based on the at least one dynamic transmission parameter may comprise at least one of: providing individual transmitter antenna configuration selections within a multiple-input multiple-output antenna array on an antenna element by element basis within an antenna sub-panel; providing individual transmitter antenna configuration selections within a multiple-input multiple- output antenna array on an antenna sub-panel by sub-panel basis; and providing individual transmitter antenna configuration selections within a multiple-input multiple- output antenna array on an antenna element polarisation by antenna element polarisation basis.

Implementing the individual antenna configuration selection within a multiple- input multiple-output antenna array by control of at least one power amplifiers and/or at least one power divider located before each antenna element may comprise at least one of: controlling at least one switch coupling a power input for the at least one power amplifier to a power supply unit; controlling at least one power supply unit coupled to at least one power amplifier; controlling the at least one power divider configured to selectively couple an output from the at least one power amplifier to antenna elements; and controlling at least one power divider of the at least one power dividers configured to selectively couple an output from the at least one power amplifier to at least one further power divider of the at least one power divider and control the at least one further power divider configured to selectively couple the output from the at least one power amplifier to the antenna elements.

Providing an individual transmitter antenna configuration selection within a multiple-input multiple-output antenna array based on the at least one dynamic transmission parameter may comprise: measuring a channel between the apparatus and at least one further apparatus based on at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array; determining at least one performance parameter associated with the measured channel for the at least two candidate individual transmitter antenna configurations; selecting one of the at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array based on the at least one performance parameter; and checking whether the selected one of the at least two candidate individual transmitter antenna configurations meet or exceed a determined performance requirement.

Measuring a channel between the apparatus and at least one further apparatus based on at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array may comprise at least one of: measuring uplink sounding in a full digital array time division duplex apparatus; measuring downlink reference signal and channel state indication feedback in a full digital array frequency division duplex apparatus; measuring downlink reference signal and channel state indication feedback in a full digital array time division duplex apparatus; measuring uplink sounding for different sub-panel configurations in a hybrid array time division duplex apparatus; measuring downlink reference signal and channel state indication feedback for different sub-panel configurations in a hybrid array frequency division duplex apparatus; and measuring downlink reference signal and channel state indication feedback for different sub-panel configurations in a hybrid array time division duplex apparatus.

The method may further comprise: measuring a channel between the apparatus and at least one further apparatus based on the at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array; calculating downlink channel covariance matrices out of estimated downlink channel matrices; and wherein selecting one of the at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array based on the at least one performance parameter may comprise at least one of: selecting highly correlated antenna elements to be switched off; selecting antenna elements based on an angular spread deduced in one or more different geometrical dimensions, the deduced angular spread defining one or more dimensions along which a number of antenna elements to be switched off is selected; and selecting antenna elements based on a spatial covariance/correlation of antenna elements in a separate horizontal and vertical directions.

Providing an individual transmitter antenna configuration selection within a multiple-input multiple-output antenna array based on the at least one dynamic transmission parameter may comprise optimizing a function of weighted sum of the at least one dynamic transmission parameter and a total required power consumption and determine at least one dynamic transmission parameter based on a selection of a set of the further apparatus out of the set of all active further apparatus and a selection of a set of antenna elements out of the set of all antenna elements within the multiple-input multiple-output antenna array.

Measuring a channel between the apparatus and at least one further apparatus based on at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array may comprise measuring a uplink channel between the apparatus and at least one further apparatus using all antenna elements within the multiple-input multiple-output antenna array as receiver antennas, and wherein selecting one of the at least two configurations within the multiple input multiple output antenna array based on the at least one performance parameter may comprise calculating one or more downlink candidate individual transmitter antenna configuration selections based on the measured uplink channel.

According to a third aspect there is provided an apparatus comprising means for: determining at least one dynamic transmission parameter; providing an individual transmitter antenna configuration selection within a multiple-input multiple-output antenna array associated with the apparatus based on the at least one dynamic transmission parameter; and implementing the individual antenna configuration selection within a multiple-input multiple-output antenna array by control of at least one power amplifier and/or at least one power divider located before each antenna element.

The at least one dynamic transmission parameter may comprise at least one of: a number of user equipment the apparatus is in communication with; a user demand parameter; locations of user equipment the apparatus is in communication with a defined transmission power; an average transmitted power in one direction during a specified time interval; a time; a date; and a mode of operation defining in which massive multiple-input multiple-output mode the apparatus is operating.

The means for providing an individual transmitter antenna configuration selection within a multiple-input multiple-output antenna array based on the at least one dynamic transmission parameter may comprise means for at least one of: providing individual transmitter antenna configuration selections within a multiple-input multiple-output antenna array on an antenna element by element basis within an antenna sub-panel; providing individual transmitter antenna configuration selections within a multiple-input multiple-output antenna array on an antenna sub-panel by sub- panel basis; and providing individual transmitter antenna configuration selections within a multiple-input multiple-output antenna array on an antenna element polarisation by antenna element polarisation basis.

The means for implementing the individual antenna configuration selection within a multiple-input multiple-output antenna array by control of at least one power amplifiers and/or at least one power divider located before each antenna element may comprise means for at least one of: controlling at least one switch coupling a power input for the at least one power amplifier to a power supply unit; controlling at least one power supply unit coupled to at least one power amplifier; controlling the at least one power divider configured to selectively couple an output from the at least one power amplifier to antenna elements; and controlling at least one power divider of the at least one power dividers configured to selectively couple an output from the at least one power amplifier to at least one further power divider of the at least one power divider and control the at least one further power divider configured to selectively couple the output from the at least one power amplifier to the antenna elements.

The means for providing an individual transmitter antenna configuration selection within a multiple-input multiple-output antenna array based on the at least one dynamic transmission parameter may comprise means for: measuring a channel between the apparatus and at least one further apparatus based on at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array; determining at least one performance parameter associated with the measured channel for the at least two candidate individual transmitter antenna configurations; selecting one of the at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array based on the at least one performance parameter; and checking whether the selected one of the at least two candidate individual transmitter antenna configurations meet or exceed a determined performance requirement.

The means for measuring a channel between the apparatus and at least one further apparatus based on at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array may comprise means for at least one of: measuring uplink sounding in a full digital array time division duplex apparatus; measuring downlink reference signal and channel state indication feedback in a full digital array frequency division duplex apparatus; measuring downlink reference signal and channel state indication feedback in a full digital array time division duplex apparatus; measuring uplink sounding for different sub-panel configurations in a hybrid array time division duplex apparatus; measuring downlink reference signal and channel state indication feedback for different sub-panel configurations in a hybrid array frequency division duplex apparatus; and measuring downlink reference signal and channel state indication feedback for different sub-panel configurations in a hybrid array time division duplex apparatus.

The apparatus may further comprises means for: measuring a channel between the apparatus and at least one further apparatus based on the at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array; calculating downlink channel covariance matrices out of estimated downlink channel matrices; and wherein the means for selecting one of the at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array based on the at least one performance parameter may comprise at least one of: selecting highly correlated antenna elements to be switched off; selecting antenna elements based on an angular spread deduced in one or more different geometrical dimensions, the deduced angular spread defining one or more dimensions along which a number of antenna elements to be switched off is selected; and selecting antenna elements based on a spatial covariance/correlation of antenna elements in a separate horizontal and vertical directions.

The means for providing an individual transmitter antenna configuration selection within a multiple-input multiple-output antenna array based on the at least one dynamic transmission parameter may comprise means for optimizing a function of weighted sum of the at least one dynamic transmission parameter and a total required power consumption and determine at least one dynamic transmission parameter based on a selection of a set of the further apparatus out of the set of all active further apparatus and a selection of a set of antenna elements out of the set of all antenna elements within the multiple-input multiple-output antenna array.

The means for measuring a channel between the apparatus and at least one further apparatus based on at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array may comprise means for measuring a uplink channel between the apparatus and at least one further apparatus using all antenna elements within the multiple-input multiple-output antenna array as receiver antennas, and wherein the means for selecting one of the at least two configurations within the multiple input multiple output antenna array based on the at least one performance parameter may comprise means for calculating one or more downlink candidate individual transmitter antenna configuration selections based on the measured uplink channel. In another aspect there is provided a computer program embodied on a non- transitory computer-readable storage medium, the computer program comprising program code for providing any of the above methods.

In another aspect there is provided a computer program product for a computer, comprising software code portions for performing the steps of any of the previous methods, when said product is run.

A computer program comprising program code means adapted to perform the method(s) may be provided. The computer program may be stored and/or otherwise embodied by means of a carrier medium.

In the above, many different embodiments have been described. It should be appreciated that further embodiments may be provided by the combination of any two or more of the embodiments described above.

Description of Figures

Embodiments will now be described, by way of example only, with reference to the accompanying Figures in which:

Figure 1 shows a schematic diagram of an example communication system comprising a plurality of base stations and a plurality of communication devices;

Figure 2 shows a schematic diagram of an example control apparatus;

Figure 3a and 3b show example MIMO transmit architectures;

Figures 4a to 4e show various antenna element use patterns;

Figure 5 shows an example analogue radio frequency (RF) frontend transmitter architecture enabling power adaption with fix assignment to antenna polarization according to some embodiments;

Figure 6a shows examples of analogue RF frontend transmitter architecture enabling power adaption with flexible antenna polarization assignment per antenna according to some embodiments;

Figure 6b shows examples of analogue RF frontend transmitter architecture enabling power adaption with flexible antenna polarization assignment for several controlled antennas according to some embodiments; Figure 7 shows a schematic diagram of an antenna element selector which may be implemented within a power controller as shown in Figures 5, 6a and 6b according to some embodiments; and

Figure 8 shows a flow diagram of an example method for implementing the control of the antenna array according to some embodiments.

Detailed description

The concept as discussed in further detail hereafter focuses on a power efficient base stations which attempts to control the required transmit (TX) power despite a larger bandwidth and higher number of users served. Thus base stations implementing embodiments of the application are configured to operate with a decreased cost of operation for the operator.

Before explaining the examples in detail, certain general principles of a wireless communication system and mobile communication devices are briefly explained with reference to Figures 1 to 2 to assist in understanding the technology underlying the described examples.

In a wireless communication system 100, such as that shown in Figure 1 , mobile communication devices or user equipment (UE) 102, 104, 105 are provided wireless access via at least one access point or similar wireless transmitting and/or receiving node or point. An access point or base station is referred to as a Node B or generally NB (for example an eNB in LTE and gNB in 5G NR). Base stations are typically controlled by at least one appropriate controller apparatus, so as to enable operation thereof and management of mobile communication devices in communication with the base stations. The controller apparatus may be located in a radio access network (e.g. wireless communication system 100) or in a core network (CN) (not shown) and may be implemented as one central apparatus or its functionality may be distributed over several apparatus. The controller apparatus may be part of the base station and/or provided by a separate entity such as a Radio Network Controller. In Figure 1 control apparatus 108 and 109 are shown to control the respective macro level base stations 106 and 107. In some systems, the control apparatus may additionally or alternatively be provided in a radio network controller. In Figure 1 base stations 106 and 107 are shown as connected to a wider communications network 1 13 via gateway 1 12. A further gateway function may be provided to connect to another network.

The smaller base stations (or relay nodes or RN) 1 16, 1 18 and 120 may also be connected to the network 1 13, for example by a separate gateway function and/or via the controllers of the macro level stations. The base stations 1 16, 1 18 and 120 may be pico or femto level base stations or the like. In the example, station 1 18 is connected via a gateway 1 1 1 whilst station 120 connects via the controller apparatus 108. The station 1 16 may be connected via station 107 as will be explained in further detail hereafter. In some embodiments, the smaller stations may not be provided.

A mobile communication device, often referred to as user equipment (UE) or terminal, may be provided by any device capable of sending and receiving radio signals. Non-limiting examples comprise a mobile station (MS) or mobile device such as a mobile phone or what is known as a’smart phone’, a computer provided with a wireless interface card or other wireless interface facility (e.g., universal serial bus (USB) dongle), personal data assistant (PDA) or a tablet provided with wireless communication capabilities, or any combinations of these or the like. A mobile communication device may provide, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and so on. Users may thus be offered and provided numerous services via their communication devices. Non-limiting examples of these services comprise two-way or multi-way calls, data communication or multimedia services or simply an access to a data communications network system, such as the Internet. Users may also be provided broadcast or multicast data. Non-limiting examples of the content comprise downloads, television and radio programs, videos, advertisements, various alerts and other information.

The mobile device may receive signals over an air or radio interface via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. The transceiver apparatus may be provided for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device and may be a single antenna or antenna array suitable for operation within multiple input multiple output (MIMO) systems. An example control apparatus (and/or base station) is shown in Figure 2. Figure 2 shows an example of a control apparatus provided in a base station or access point. The control apparatus 300 comprises at least one memory 301 , at least one data processing unit 302, 303 and an input/output interface 304. Via the interface the control apparatus can be coupled to a receiver and a transmitter of the base station. The receiver and/or the transmitter may be implemented as a radio front end or a remote radio head. For example the control apparatus 300 or processor 302/303 can be configured to execute an appropriate software code to provide the control functions.

An example of wireless communication systems are architectures standardized by the 3rd Generation Partnership Project (3GPP). The currently being developed 3GPP based development, release 15, is often referred to as the 5G NR standards part of long-term evolution (LTE) or LTE Advanced Pro of the Universal Mobile Telecommunications System (UMTS) radio-access technology. Other examples of radio access system comprise those provided by base stations of systems that are based on technologies such as Multefire (or other unlicensed access such as LTE-U), wireless local area network (WLAN) and/or WiMax (Worldwide Interoperability for Microwave Access).

The high capacity capabilities of a massive multiple-input multiple-output (MIMO) system can be achieved only if the number of simultaneously served users is high and the users are well spatially distributed within a cell (in other words the number of spatially separated MIMO layers is high). To provide sufficiently high transmit power with the corresponding beam pattern at the full bandwidth each antenna element (or groups of antenna elements) is equipped with a power amplifier (PA). The power amplifier has a limited PA efficiency. This PA efficiency determines the overall power consumption of all PAs in the base station and contributes to a considerable part to the overall power consumption of the base station.

In practical deployments the number of simultaneous users varies significantly over time. Thus in some situations there may be a significant amount of time where there are only a few users which are simultaneously active. Simulations have shown that for a small number of users the achievable spectral efficiency is poor, despite of a large number of antenna elements. Therefore, in such cases the system cannot make full use of the overprovisioning of base station capabilities and power consumption is still as high as it would be for a higher number of users. A more detailed analysis of hardware components further shows, that the PA is the most dominant contributor to the overall power consumption, especially when TX power values as required for beyond 100 MHz bandwidth and/or large cell coverage (requiring high Equivalent Isotropically Radiated Power - EIRP) are assumed.

There are two basic architectures that are supported in the embodiments described hereafter.

A first architecture is a hybrid architecture, where the different digital streams or MIMO layers are mapped to subarrays or sub-panels. In the hybrid architecture, only the combined signal of the elements of the sub-panels are available for measurements.

With respect to Figure 3a an example of the first MIMO transmitter architecture suitable for use in different embodiments is shown. This architecture suitable for a massive MIMO antenna system is also known as a hybrid array architecture.

The input signal streams or MIMO layers Si to SK 400, which in some embodiments are the signal streams for each active UE are input to a digital pre-coder 401 .

The digital pre-coder 401 receives the signals and distributes these streams on a number of ports P, which can be seen as antenna port streams ti to tp 402. The port streams 402 are then each output to an analogue antenna sub-array. Thus for example the digital pre-coder 401 is configured to output each stream to a digital to analogue (D/A) block 403 for generating analogue signals. The analogue signals for each antenna port are passed to a radio frequency (RF) chain 405 (represented in Figure 3 by the RF chain 1 (for port 1 ) to RF chain P (for port P)), which provides upconversion of the analogue signal to the carrier frequency. The output of the RF chain 405 is passed to an analogue pre-coder shown as pre-coder ai (for port 1 ) to a_P (for port P), each of which are Mx1 matrix operations and configured to output to antenna sub-arrays each comprising antenna elements 1 to M. The antenna sub- arrays combine to form the complete MIMO antenna 409, so that the full antenna array contains P^*M elements. The overall TX power is generated by the PAs 408 connected to each antenna element.

The concept as discussed in further detail hereafter is one of controlling the multi-antenna structure dynamically based on a determination of a simultaneously active number of users by switching off a part or parts of the PAs. A second architecture may be a full digital architecture where each antenna element is connected to an AD/DA converter, so that each individual antenna signal is accessible for processing.

With respect to Figure 3b an example of the second MIMO transmitter architecture, the full digital architecture, suitable for use in embodiments is shown.

The digital pre-coder 401 receives the signals and distributes these streams on a number of ports P, which can be seen as antenna port streams ti to tp 402. The port streams 402 are then optionally passed to a series of sub-array pre-coder 417 shown as sub-array pre-coder ai (for port 1 ) to a_P (for port P), each of which are Mx1 matrix operations and configured to output to a set of digital to analogue converters 413 for each sub-array element 1 to M stream.

In some embodiments the ports exist where the digital precoder provides fewer streams than antenna elements, and the subarray precoder provides additional streams for the subarrays.

In some embodiments there may be a further architecture variant. This variant comprises a single“subarray precoder”, which realizes a distribution of all P ports to all M^*P antenna elements. In such embodiments it may be possible to only switch off/on antenna elements, not ports, because each“port” uses all antenna elements for transmission.

In some embodiments the digital pre-coder outputs the port streams directly to an array of digital to analogue converters 413.

In such embodiments every port is connected to one antenna element, there is only 1 array and thus it may be possible to only switch off/on antenna elements.

The digital to analogue converter 413 are then configured to output for each stream and for each antenna element a suitable analogue signal. The analogue signals for each antenna port and element are passed to a radio frequency (RF) chain 415 (represented in Figure 3b by the RF chain 1 1 to RF chain M1 for port 1 and RF chain 1 P to RF chain MP for port P), which provides up-conversion of the analogue signal to the carrier frequency. The output of the RF chain 405 is passed to the PAs 408 connected to each antenna element. Furthermore the concept is one of controlling the dynamically selected multi- antenna structure to select the number, location and transmission (Tx) power of active antenna elements according to some determined cell or domain parameters. In embodiments as discussed hereafter at least one individual transmitter antenna configuration selection is provided based on a determined dynamic transmission parameter and implemented by control of at least one power amplifier and/or at least one power divider located before each antenna element. Example dynamic transmission (cell or domain) parameters may be the number of simultaneously served UEs within the cell, the radio channel properties of the served UEs, an average transmission power over a determined period and the distribution and individual traffic requirements of the served UEs. This individual transmitter antenna configuration selection may be performed in some embodiments such that the overall power consumption (or number of active PAs and related TX power) applied to serve the simultaneously scheduled UEs is minimized while maintaining the target performance.

The individual transmitter antenna configuration selection (in other words a selection at the level of individual antenna elements within the antenna array) may be performed in some embodiments by selecting (virtually or physically) antenna ports to be active and/or inactive. Thus one manner to control the multi-antenna structure is to reduce the number of antenna ports by selecting antenna elements on a sub-panel or sub-array basis reducing or increasing the number of sub-panels or sub-arrays and therefore reducing or increasing respectively the overall array size (for example switching off or switching on sub-arrays according to the number of users). This is known as switching or controlling on a sub-panel by sub-panel basis.

The individual transmitter antenna configuration selection of the antenna elements may be performed in some further embodiments by selecting individual antenna elements within each sub-panel or sub-array. This is known as switching or controlling on an antenna element by element basis. In this manner the antenna structure may be controlled to reduce the used number of antenna elements within a sub-panel or to increase the used number of antenna elements within a sub-panel. In other words to change the pattern of the sub-arrays. This approach has the advantage that the antenna aperture can be maintained (depending on the selection of antenna elements) and the degrees of freedom for MIMO precoding will remain. In such embodiments what changes is the individual sub-panel antenna pattern and, as the target of the proposed solution, the overall TX power and therefore the power consumption is based on the number of simultaneous users.

The selection of the antenna elements may be performed in some further embodiments by selecting individual antenna elements where each individual antenna element is a polarization element of the antenna. This is known as switching or controlling on an antenna element polarisation by antenna element polarisation basis.

The selection of the antenna elements may be performed in some embodiments to select individual antenna elements out of the full array which contribute significantly to performance.

Although in principle it may be possible to adapt the TX power of a PA in a continuous manner while the array shape is kept fixed, this requires calibrated hardware and additional effort, whereas the proposed switching method, in combination with a selection criteria (which for example is the based on the number of UEs) is simpler and faster and therefore can be applied in a highly dynamic manner.

The embodiments are further described in further detail with respect to the following example. In the following example there is assumed to be K = 1 ... 32 UEs / MIMO layers, the data streams from each of the UEs are mapped to P = 64 antenna ports, and each of the ports are coupled to sub-arrays comprising M = 4 antenna elements per subarray. In other words there is an antenna array with 256 antenna elements.

Some potential dynamic switching approaches when applied to an example array sub-panel (4 rows x 8 sub-panels with 4 cross-polarized elements, each) are shown in the Figures 4a to 4e. Figure 4a to 4e show usage configurations or selections where the columns 503 represent sub-panels (or sub-arrays) comprising 4 elements shown as the rows 501 , thus for example a first sub-array may be represented by the first column and top four rows 505 and a 32^nd sub-array may be represented by eighth column and bottom four rows 507.

Thus Figure 4a shows a full usage transmitter antenna configuration or selection 51 1 where each element in each sub-array is active. Figure 4b shows a first reduced usage transmitter antenna configuration 513 where only half of the elements in each sub-array is active but in each sub-array there are two active elements per sub-panel. Figure 4c shows a further reduced usage configuration 515 where only one element per sub-panel is active. Figure 4d shows a further reduced usage transmitter antenna configuration where the reduction is performed by switching off complete sub-panels. In such embodiments complete sub-panels are switched off instead of adapting the number of radiating elements per sub-panel. This method impacts the number of antenna ports and therefore reduces the degrees of freedom to pre-code the simultaneous MIMO streams, which results in a larger impact on performance. Figure 4d shows a transmitter antenna configuration 517 where 16 out of 32 sub-panels are switched off (no x marked in the sub-panels), the result of switching off one half of the sub-panels of the array 503 in Figure 4a. For example the first sub-panel 505 is completely on and the last or 32^nd sub-panel 507 is completely off.

Figure 4e shows a further reduced usage transmitter antenna configuration 519 where 8 out of the remaining 16 sub-panels shown in Figure 4d in pattern 517 are switched off. In some embodiments the number of MIMO streams/M I MO layers 400 K that can be supported by a number of ports P is up to P/2. In other words typically K£P/2. In usual MIMO operation the total transmitter (TX) power is distributed among all active users. When the number of users decreases, the total TX power can be reduced accordingly, maintaining in average the same TX power per user.

The embodiments thus as discussed herein describe a process wherein the controller is configured to switch off half of the elements per sub-panel, while the other elements remain active as before. If the number of UEs further decreases, more elements per sub-panel can be deactivated, down to 1 remaining active antenna element per sub-panel.

Figure 5 shows an example analogue RF transceiver concept level view of some embodiments showing individual adaptive PA supply voltage adaptation or PA on-/off-switching and therefore supporting the idea of on-/off-switching related to current user demand. For example on-/off-switching of antenna sub-panels or elements within a sub-panel of multi-antenna massive MIMO arrays related to current user demand.

In the example shown in Figure 5, the functionality of the system shown in Figure 3a including the analogue pre-coder and RF chain is shown in further detail. The example shown in Figure 5 shows a digital RF unit 601 configured to output digital signals to an analogue module 600. The analogue module 600 comprises a single RF conversion (digital-to-analogue-conversion, analogue-to-digital-conversion, up- conversion and down-conversion) unit 603 configured to control four or more antennas including power amplification, filtering and phase shifting. In some embodiments there may be more than one conversion unit. For example in some embodiments there may be several transceiver (TRX) conversion units integrated in a common package (a Multi-TRX conversion unit). In this case accordingly more antennas including power amplification, filtering and phase shifting to be controlled by the accordingly further TRX conversion units can be connected to the multi-TRX conversion unit.

In this example the conversion unit 603 is coupled to a single splitter 605 configured to split the input signal into four streams. These four streams are passed to individual phase shifters 607, power amplifiers 609 and antenna filters 61 1 being passed to the antenna elements 613.

In such a manner the analogue precoder 407 shown in Figure 3a comprises only the phase shifters 607 and may be (depending on the view) also the power amplifier 609 (any amplitude coding, could in this case also be a kind of variable gain amplifier). The conversion unit 603 shown in Figure 5 and the splitter 605 (and may be amplifier 609) may correspond to the RF chain 405 shown in Figure 3a. However it would be understood that because of different exemplarily embodiments of analogue RF architectures a direct and explicit mapping of functional blocks of Figure 5 to functional blocks of Figure 3a and 3b may change. In order to allow for individual power supply voltage adaptation as well as individual power amplifier on-/off switching, a power control unit (an example of which is shown in Figure 5 by 610) is connected individually to each of the power amplifiers (PAs) 609, allowing for individual supply voltage adaptation and on-/off-switching.

In this example all of the power amplifiers 609 are supplied by a common central power supply unit (PSU) 608 providing a common fixed maximum supply voltage.

In the example shown in Figure 5 each of the individual power control units 610 are controlled by a power controller 606. The power controller 606 may be configured to control the operation of the individual power control units 610 based on a determination of the number of active users. The power controller is shown in Figure 5 as being located within the analogue RF frontend 600. The power controller 606 may be configured to receive information from the digital/base band unit 601 or other suitable device such as, for example the number of UE to be supported. In some embodiments the power controller may be placed in the digital RF frontend unit 601 or other suitable digital unit and be configured to support interfaces to the analogue RF unit 600 in order to control supply voltages and, if necessary, in some embodiments control adaptive power dividers.

In some embodiments the control of supply voltages (and furthermore power dividers) could also be implemented by different blocks and even in different entities, where suitable. In some embodiments the information or control is generated within a common central unit, the common central unit configured to have knowledge about the number of current users to be served, and other parameters.

In such embodiments there is provided a high degree of flexibility with respect to phase and supply voltage adjustment, and enables low losses after the power amplifier (as the phase shifters are located at PA input side), but requires a large number of power amplifier devices and antenna filters.

A further example analogue pre-coder is shown in Figure 6a. The main difference of the examples 700a, 700b and 700c shown in Figure 6a compared to Figure 5 is, that the two polarizations of the common antenna per TX path are controlled via the same power amplifier.

In such examples in order to enable a switch-on/-off of the TX power individually per antenna polarization, a switchable power divider 701 is used, allowing individual control of both polarizations of the antenna with half the TX power, each, or to direct the full (or reduced, depending on power amplifier biasing) TX power either to +45° or -45° polarized antenna. Thus the power controller is shown coupled to each of the switchable power dividers and configured to control them based on the determined number of UEs.

The difference between the examples 700a, 700b, and 700c is the position and number of the phase shifters and thus flexibility for individual phase alignment and different impact on efficiency.

Thus for example the example 700a shows apparatus where a phase shifter is located before the power amplifier and switchable power dividers. Such an example allows for common phase alignment of both antenna polarizations, but with lower loss after the power amplifier since the phase shifters are placed at the power amplifier input. The energy efficiency furthermore in such examples is less affected and is higher. The example 700b shows apparatus where a phase shifter is located after the power amplifier (and filter) but before the switchable power dividers. In this case, again both antenna polarization are phase controlled using a common control. Such an example may add some extra losses at the output of the power amplifier, reducing energy efficiency.

The example 700c shows apparatus where a phase shifter is located after the power amplifier and switchable power dividers and as such allows individual phase alignment of each antenna polarization of each antenna, but at the expense of needing twice the number of phase shifters (compared to the examples 700b and 700a) and the phase shifters add some extra loss on the output side of the amplifier, reducing energy efficiency.

As discussed above individual power amplifier supply voltage adjustment, as well as individual power amplifier on-/off-switching is again achieved by the common power controller coupled to individual power supply adjustment units. Furthermore the common power controller may be configured to control the controllable power dividers allowing for antenna polarization individual selection.

Figure 6b shows a further group of example apparatus according to some embodiments. The examples shown 800a, 800b, 800c differ from the examples shown in Figure 6a in that each power amplifier is configured to controlling two or more antennas (where each antenna may have two polarizations). These examples produce apparatus which further reduces number of power amplifier required (but not reduced total required transmit power).

In order to achieve the reduction in the number of power amplifiers the examples comprise additional (for example one per antenna) controllable power dividers 801 which are added into the transmit paths after the power amplifier. These additional adaptive power dividers are also controlled by the common power controller.

The difference between the examples 800a, 800b, and 800c are the position and number of the phase shifters which defines flexibility (increased phase adaptation flexibility per TX antenna polarization from example 800a to 800b to 800c) and losses on power amplifier output side (increasing losses from example 800a to 800b to 800c). Thus example apparatus 800a shows a phase shifter located before the power amplifier and switchable power dividers. Such an example allows for common phase alignment of both antenna polarizations of both antennas, but with lower loss after the power amplifier since the phase shifters are placed at the power amplifier input. The energy efficiency furthermore in such examples is less affected.

The example apparatus 800b shows apparatus where a phase shifter is located after the power amplifier (and filter) and the additional controllable power adaptors but before the switchable power dividers, which allows for common phase alignment of both antenna polarizations, but individually for each antenna. Since the phase shifters are positioned at the power amplifier output side, output losses after the power amplifier are increased compared to previous example 800a.

The example 800c shows apparatus where a phase shifter is located after the power amplifier and switchable power dividers and as such allows individual phase alignment of each antenna polarization of each antenna, but at the expense of needing four times the number of phase shifters (compared to the example 800a) and twice the number of phase shifters (compared to example 800b) and the phase shifters add some extra loss on the output side of the amplifier, reducing energy efficiency.

Associated with the number of data streams and number of controlled antennas, the example apparatus shown in Figure 5 supports full massive MIMO and/or beamforming for all antennas and all antenna polarizations. The apparatus shown in Figure 6a supports massive MIMO and beamforming only on individual antenna level but not on individual antenna polarization. The apparatus shown in Figure 6b supports massive MIMO and beamforming only on sub-array level.

The operation of the common power controller, such as shown by reference 606 in Figure 5, configured to control which antennas are currently used as well as which related antenna polarization (only one or both) is used and with which individual TX power (power amplifier supply voltage adjustment) is described in further detail hereafter.

In some embodiments the common power controller may be configured to implement the control in a mutual coordinated manner for the full antenna array. Thus for example the common power controller may be configured to control the power amplifier and/or switchable power divider based on a parameter other than the number of user equipment as discussed above. For example in some embodiments the common power controller is configured to determine parameters related to the currently specific application, user demand (number of users to be served, location of users, required TX power, day or night time, etc.) and mode of operation (massive MIMO, beamforming) and implement control based on these.

The implementation of which of the embodiments shown in Figures 5, 6a, and 6b may be determined based on the specific target application. For example a specific embodiment apparatus may be implemented based on a required or desired flexibility per antenna/per antenna polarization, as well as on requirements like cost, power consumption, circuit complexity.

With respect to Figure 7 an example antenna element selector or provider of individual transmitter antenna configuration selections, which may be implemented within the common power controller as shown in Figure 5, 6a, and 6b is shown in further detail.

The selector in some embodiments comprises a parameter determiner 751 , a candidate selector 753, candidate evaluator/optimiser 755 and a selector verifier 757.

In some embodiments the parameter determiner 751 is configured to receive or determine a cell and/or transmitter antenna configuration related parameter to be evaluated. This parameter may be known as a dynamic transmission parameter as it is evaluated dynamically and concerns the transmission aspects of the antenna or cell the apparatus is operating within. As discussed above the (cell and/or antenna configuration) parameter may be any suitable parameter such as at least one of the number of user equipment, current specific application, user demand (number of users to be served, location of users, required TX power, day or night time), mode of operation (massive MIMO, beamforming) and average transmitted power in one direction during a specified time interval. The average transmitted power parameter is monitored as it is required by regulatory means that a specific field strength (for example 61 V/m or equivalent expressed EIRP level) averaged over a defined period of time is not exceeded.

In some embodiments as described later the parameter determiner 751 may be further configured to compare the determined parameter to a known or defined parameter threshold value and be configured to control the dynamic selection of antenna elements based on the relationship between the determined parameter and the parameter threshold value.

For example in some embodiments the parameter may be the number of active UEs and the parameter determiner is configured to check when the number of active UEs is below a certain threshold. A threshold in some embodiments may be defined relative to the sub-arrays and may be mathematically defined as A^* P/2, with A <=1 . In some other embodiments this threshold may be the regulatory approved average transmitted power over a defined period of time.

The parameter determiner 751 may therefore inform a candidate selector 753 that an individual transmitter antenna configuration selection within a multiple-input multiple-output antenna array is to be made.

The candidate selector 753 in some embodiments is configured to receive an indication or message from the parameter determiner that an individual transmitter antenna configuration selection is to be made. Furthermore in some embodiments the determined parameter may also be passed from the parameter determiner. The candidate selector 753 may be configured to select one or more candidate individual transmitter antenna configuration selections, in other words a selection of individual elements of the antenna array based on the determined parameter.

In some embodiments the candidate selector 753 is configured to receive an input identifying the current individual transmitter antenna configuration and furthermore determine the candidate individual transmitter antenna configuration(s) based on the current individual transmitter antenna configuration and the determined parameter. Furthermore the candidate selector 753 in some embodiments is further configured to receive a feedback input from the candidate evaluator/optimiser 755 and determine further candidate individual transmitter antenna configuration(s) based on the feedback from the candidate evaluator/optimiser 755.

The candidate evaluator/optimiser 755 is configured to receive the selected candidate individual transmitter antenna configuration(s) and evaluate these further based on calculating performance parameters. The performance parameters may be based on measured or calculated channel values.

In some embodiments the candidate evaluator/optimiser 755 selects one of the candidates and passes it to the selection verifier 757. In some embodiments the candidate evaluator/optimiser 755 operates a feedback loop with the candidate selector 753 wherein a feedback message or signal is passed back to the candidate selector 753 which generates further candidates until a candidate individual transmitter antenna configuration(s) produces a sufficiently good performance parameter value or the best performing individual transmitter antenna configuration is found. The selection verifier 757 can furthermore be configured to receive the selected candidate and check whether the performance of the selected candidate individual transmitter antenna configuration is acceptable and then implement the selection, for example by providing the control signals to the power dividers (power splitters) or power amplifiers associated with the antenna elements.

In such a manner a combination of the selection verifier and the candidate evaluator/optimiser may be considered to select an individual transmitter antenna configuration based on the at least one dynamic transmission parameter.

With respect to Figure 8 is shown a flow diagram showing a method for implementing the control of the antenna array based on determined cell parameters, for example a method of operating the example antenna element selector shown in Figure 7. For example Figure 8 specifically shows the adaptation of the antenna array based on a number of simultaneously served UEs, however any other suitable cell based or network based parameter may be used.

The selection or control procedure may start with a monitoring of at least one cell/antenna configuration parameter(s) (e.g. number of [simultaneously] served UEs, beam directions/weights and time duration, other cell parameter) as shown in Figure 8 by step 901.

The procedure may continue with a determination of whether the monitored parameter is acceptable. For example is the number of UEs (and/or cel! parameter usage) high? Does the transmission power not exceed regulatory limits? This check is shown in Figure 8 by step 903.

In addition, if available, the service requirements for each UE could be taken into account for the decision to serve them simultaneously. The check is used to consider changing the adaptation of the antenna, for example switching off elements, if the number of active UEs is below a certain threshold. Thus UE high threshold may be defined relative to the number of ports and may be mathematically defined as A^* P/2, with A <=1.

Where the parameter is acceptable (e.g. the number of UEs is high/TX power is below regulatory limits etc.) then the current configuration may be maintained as shown in Figure 8 by step 915.

Where the parameter is not acceptable for example a‘trigger’ threshold is met (e.g. number of UEs is small, the cell parameter usage low, the TX power limit is exceeded etc.) then one or more candidate antenna element configurations to attempt to improve the parameter may be selected as shown in Figure 8 by step 905. In some embodiments an initial configuration may be determined based on the determined parameter or may practically be realized by selecting (or switching) between several fixed array pre-configurations.

Having a proposed antenna element adaptation the next operation is one of estimating or measuring channels between the base stations and UEs as shown in Figure 8 by step 907. The measurement procedures implemented may be dependent on the different array architectures, operation modes and on the intended array adaptation procedure. The measurement/determination of the channels is supported for full digital and hybrid array architectures.

For example for a Time division duplex (TDD) full digital array architecture uplink sounding measurements may be measured/determined. For a TDD hybrid array architecture an uplink sounding for different sub-panel configurations may be measured/determined. In some embodiments for a frequency division duplex (FDD) full digital array architecture downlink reference signals and explicit channel state information (CSI) feedback may be measured/determined. For a FDD hybrid array architecture downlink reference signals and explicit channel state information (CSI) feedback for different sub-panel configurations may be measured/determined.

Also both, the adaptation in steps of pre-configured array structures and the adaptation by selection of individual elements to switch off (as shown exemplarily in Figures 4a to 4e) are possible, but will have different impact on the overall procedure.

Having estimated the channels based on the selected proposed adaptation and full array usage and/or current adaptation the system may then determine a performance criterial as shown in Figure 8 by step 909.

Then the system may determine whether the performance is optimised as shown in Figure 8 by step 91 1.

For the optimization of the array adaptation the measurements and selection procedures can be designed to support different optimization goals.

For example an optimization goal may be:

To fulfill a certain minimum service quality for a high percentage of users (99% or 95%);

To optimize the instantaneous power efficiency vs. e.g. weighted sum rate; To optimize a long-term power efficiency with respect to spectral efficiency or cell border throughput or another minimum service requirement; and

T o optimize the exploitation of spatial diversity (or to reduce the number of used TX antenna elements in cases of poor spatial diversity).

All of these goals may aim at a reduction of the transmitted power and of the power consumption of the system, while maintaining different target key performance indicators (KPIs). In this sense, the embodiments are designed to be flexible enough to address various applications.

In some embodiments the load in the system is measured. For example as a percentage of used resources. Furthermore in some embodiments the worst-case service quality (e.g. the cell border throughput) is evaluated. Based on a threshold some embodiments are configured to reduce the power consumption of the system by switching off antenna components (subarrays or physical antenna elements).

Having determined that the system is not optimised then the system may be configured to loop back and select a further antenna element configuration candidate where a determination of which elements to switch off can be based on further information about the channel matrices and channel qualities of the active mobiles in the cell.

For a TDD full digital (calibrated) array, this calibration allows explicit channel knowledge for all active mobiles within a cell. Obtaining channel knowledge can be based on carrying out sounding with sounding reference signals (SRS). The uplink (UL) measurement corresponds to the UL channel matrix H_UI,I for every mobile I out of the L active mobiles in the cell. To enable the prediction of throughput, the following elements are determined:

Channel attenuation per mobile;

Extra cell interference for every mobile I out of the set of all active mobiles L;

Assumption about the type of receiver in the mobile (e.g. IRC); and

BS transmit power per TX antenna element.

The channel attenuation can furthermore be deduced from the sounding reference signal (SRS) receive and transmit signal level. Hence, the UE’s current TX signal level is known by the base station. The extra cell interference can be deduced either from a channel quality indicator (CQI) level that is reported by a UE, which corresponds to a signal to interference and noise ratio (SINR) value, or by an explicit extra cell interference level reported by the UE.

Furthermore the downlink (DL) channel matrices H_di,i can be estimated for every active mobile I in the cell. Based on the mMIMO algorithm used (e.g. Zero Forcing or Eigen Beam Forming), the receive signal level, the intra cell interference, and the extra cell interference can be estimated, i.e. the SINR for every mobile L can be estimated for any set of co-scheduled users and for any set of TX antenna elements that are switched on based on the CQI. From SINR the system can estimate the achieved throughput.

In some embodiments where the optimization is determined on a per scheduling basis, the system can be configured to optimize a function of weighted sum rate (WSR) and the total required power consumption (PWC). In some embodiments the system is configured to optimize the performance by selecting a set of mobiles L, out of the set of all active mobiles L and a set /V, of TX antenna elements out of the set of all TX antenna elements A/:

For long term optimization, the system in some embodiments is configured to deduce the downlink channel covariance matrices out of the estimated downlink channel matrices Hdij.

From these covariance matrices, the system can be configured to deduce highly correlated TX antenna elements and switch them off. In some embodiments the system may be configured to deduce the average angles from the downlink channel covariance matrices under which the mobiles (or the corresponding reflectors in case of Non Line of Sight, NLoS) are visible by the BS antenna, corresponding to the strongest Eigenvectors of the channel covariance matrices. Furthermore the system may also be configured to determine the channel angular spread information out of SRS by computing the spatial covariance / correlation of antenna elements separately in horizontal and vertical direction. A higher element correlation in vertical direction typically is associated to lower vertical angular spread. This UE angular spread shows if the angular spread is higher in the horizontal domain, or in the vertical domain. When switching off TX antenna elements, in some embodiments the selection is performed considering the serving of the dominant domain, horizontal or vertical, by a larger set of TX antenna elements. This is achieved by reducing the number of active radiating antenna elements (“thin out the array”) in dimension of lower angular spread by switching of elements and respective RF/conversion chains. In such embodiments spatial processing remaining available in the other dimension can be sufficient to exploit the channel properties.

Furthermore, in some embodiments the system is configured to optimize a predicted cell spectral efficiency (SE) or minimum service quality, e.g. a minimum required cell border throughput (CBTP) in relation to total power consumption (PWC), based on the extreme opposite assumption that all UEs are either served in SU-MIMO or in full MU-MIMO mode. argmax

/(SE, PWC)

Ni e N

or

argmax

/(CBTP, PWC)

N e N

This may practically be realized by a controller or means for controlling selecting (or switching) between several fixed array pre-configurations (such as shown in Figures 4a to 4e). Switching off elements can be applied independently in horizontal and vertical directions, addressing adaptations of degrees of freedom for MIMO layers separately in horizontal and vertical directions. Elements are switched off by“thinning out” the array in the direction with lower angular spread, as the channel is“less rich” in this direction.

In embodiments operating within a TDD hybrid array architecture (in a manner as discussed previously), the system is configured to measure the uplink channels H_UI,I and deduce the downlink channel matrices Hdi,i. However these embodiments may differ from the above method in that in contrast to the previous case, the measurement is done based on the different configurations of BS antenna sub-panels (e.g. full sub- panels, half-size sub-panels, etc.). Consequently, in such embodiments the system is configured to measure different uplink channel matrices. For example to measure the parameters for a set of full sub-panels and, separately, for a set of half-size sub- panels. The optimization procedure in such embodiments may have different parameters, such as:

Switch on/off sub-panels/TX ports (this has an impact on the size of the H matrices); and

Switch on/off physical TX elements within a sub-panel (this option keeps the size of the H matrices constant but has impact on the channel coefficients).

For both cases (switching on/off complete sub-panels or reducing/enhancing the size of the sub-panels), the optimization procedure can be implemented in the same way as for the TDD/Full Digital case as discussed earlier.

In some embodiments to reduce the search space, the decisions can be made in 2 stages:

Decide for reduction of ports vs. reduction of sub-panel size; and

Decide for the concrete configuration (either the concrete ports that shall be switched off or the size of the sub-panels).

For the decisions, a sounding may be carried out twice or more in a time consecutive manner with different sets of active elements in the sub-panel.

For frequency division duplex Full Digital Array systems any existing pre-coding matrix indicator (PMI) / channel quality indicator (CQI) information or newly proposed techniques, for example explicit CSS feedback can be used to obtain the channel knowledge. In embodiments implementing explicit feedback, the same procedures may be applied as described above for a corresponding TDD system with full digital antenna systems.

For frequency division duplex hybrid Array systems in embodiments implementing explicit feedback, the same procedures as discussed previously for a TDD system with hybrid array antenna systems may be employed. In embodiments where only whole subarrays are switched on/off the system may be configured to deduce all required information from the explicit channel feedback measured by the mobiles which is based on the pre-coded per-sub-panel CSI-RS.

In some embodiments where the system has to determine information about channel matrices for reduced sub-panels (e.g. half-size sub-panels where half of the physical antenna elements are switched off), the CSI-RS must be switched, e.g. periodically, to the reduced setup of sub-panels. The UEs must be aware of the periodic CSI-RS switching to be able to assign the measurement to the correct antenna configuration. To reduce the signalling effort for these different antenna configurations, only neighbour states are measured, e.g. full size and half size sub- panels, if the system currently uses full size sub-panels, or half size and ¼ size sub- panels, if the system currently uses half size sub-panels and is not in a high load state. In some embodiments the optimization operation furthermore ensures that switching off elements does not cause a loss of coverage. This can be implemented by checking the SINR of different users to be above a certain threshold. In other words the system is configured to verify or validate the selected adaptation and apply it as shown in Figure 9 by step 913.

As typically coverage bottlenecks occur in the uplink in the embodiments implemented the system allows for different numbers of active elements in the uplink compared to the downlink. Thus in some embodiments within the downlink certain PAs may be turned off, and thus certain elements are deactivated while in the uplink all elements are activated to prevent loss of coverage. For certain SRS measurements in the hybrid-array TDD case when channel reciprocity is exploited and the downlink operates with reduced size sub-panels, uplink elements may be deactivated to the same anticipated or tested downlink configuration. The deactivation may be a‘virtual’ deactivation where a measurement of the complete uplink (UL) channel matrix is performed, while the matrix for the downlink (DL) may be calculated out of an accordingly reduced UL matrix. Regular data transmission and sounding for other purposes not related to element deactivation may however use all available array elements.

In some embodiments in TDD systems it is possible to use the full uplink measurements and calculate different options for reduced downlink antenna configurations.

UE throughput in some embodiments is monitored and compared with estimated UE throughput. In the situation where a large discrepancy between the UE and expected UE throughput occurs a new selection procedure or a switching to the next step of preconfigured array configurations can be applied.

In some FDD embodiments switched off elements are turned on occasionally for full channel measurements to check whether conditions have changed and new selection optimization needs to be started. Especially for FDD operation in case of PMI, CQI, Rl reporting an equivalent multiple-input single-output (MISO) channel can in some embodiments be calculated out of the reported optimal precoding. However, this equivalent MISO channel already comprises the receive weights. Furthermore, these reports use a very coarse quantization of phase and amplitude. Consequently, if a decision is taken about the used TX elements or TX subarrays, the decision must be checked by evaluating subsequent CQI reports (consisting of PMI, CQI, Rl). Also in such embodiments a conservative or small decrement switching towards smaller antenna setups is implemented.

Having determined the optimal adaptation configuration, the optimal adaptation configuration is then implemented as shown in Figure 8 by step 913.

In such a manner the described embodiments of the analogue RF frontends can be applied to the antenna panels and sub-panels providing the required flexibility for on-/off-switching and transmit power adaption.

The common power controller may be configured such that individual antenna elements can be switched on and off even if one PA is used to serve more than one radiating element. In some embodiments the controlling of the antenna configuration selection using the examples discussed allows selection of antenna elements to switch off and in this way adapting the effective array structure. In the following analysis it is assumed that one PA per radiating antenna element is used.

A first example of the selection is one of switching off elements within a sub- panel. This example selection may be beneficial in an Urban Macro scenario as defined in 3GPP standardization. Switching off antenna elements maintains the horizontal structure of the array, whereas in vertical direction the beam width decreases. Furthermore the sub-panel spacing also remains by switching the elements within a sub-panel. Since these effects occur in combination with a lower number of simultaneous UEs there is no dramatic impact on performance of individual UEs.

In each operation of switching off a part of the antenna elements the TX power is reduced, when switching off half the number of elements the TX power is reduced by one half (3dB). The schemes in Figure 4c and Figure 4e have a TX power which is 6 dB lower than for the original array with 256 active antenna elements - where half of the elements are switched off. If more elements are switched off, the factors differ, or if additionally the power amplifier supply voltage has been adapted, which also impacts transmit power.

These calculations for switching on/off antenna elements impacting on the transmission power level, are valid for the following conditions:

In the embodiments shown in Figure 5, half of the elements have been switched off and no amplifier supply voltage adaptation has been implemented for the active paths;

In the embodiments shown in Figure 6, again, if half of the elements have been switched off and amplifier supply voltage has been adapted suitably for the still active elements, since always two antenna polarizations are controlled by the same amplifier;

In the embodiments shown in Figure 7, if half of the elements are switched off and amplifier supply voltage has been suitably adapted for the still active elements, since one PA is controlling two antennas with 2 polarizations, each.

If we switch off on sub-panel level this differs again, depending on the respective assignment of the antenna elements to the sub-panels.

An analysis of base station hardware components reveals that the PAs are the main contributors to the overall power consumption. Since the PA efficiency is often only in the range of 25% - 35%, the power consumption of a PA with TX power P is in the range of P/0.25 ... P/0.35. Thus by controlling the TX power, a significant amount of the PA power consumption can be controlled.

It should be understood that each block of the flowchart of the Figures and any combination thereof may be implemented by various means or their combinations, such as hardware, software, firmware, one or more processors and/or circuitry.

It is noted that whilst embodiments have been described in relation to one example of an unlicensed spectrum network, similar principles maybe applied in relation to other examples of networks. It should be noted that other embodiments may be based on other cellular technology other than LTE or on variants of LTE. For example, some embodiments may be used with so-called 5G New Radio or MulteFire. Therefore, although certain embodiments were described above by way of example with reference to certain example architectures for wireless networks, technologies and standards, embodiments may be applied to any other suitable forms of communication systems than those illustrated and described herein. It is also noted herein that while the above described example embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

It should be understood that the apparatuses may comprise or be coupled to other units or modules etc., such as radio parts or radio heads, used in or for transmission and/or reception. Although the apparatuses have been described as one entity, different modules and memory may be implemented in one or more physical or logical entities.

In general, the various embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects of the invention may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The embodiments of this invention may be implemented by computer software executable by a data processor of the mobile device, such as in the processor entity, or by hardware, or by a combination of software and hardware. Computer software or program, also called program product, including software routines, applets and/or macros, may be stored in any apparatus-readable data storage medium and they comprise program instructions to perform particular tasks. A computer program product may comprise one or more computer-executable components which, when the program is run, are configured to carry out embodiments. The one or more computer-executable components may be at least one software code or portions of it.

Further in this regard it should be noted that any blocks of the logic flow as in the Figures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example digital versatile disk (DVD) and the data variants thereof, compact disk (CD). The physical media is a non-transitory media.

The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may comprise one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), FPGA, gate level circuits and processors based on multi core processor architecture, as non-limiting examples.

Embodiments of the inventions may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

The foregoing description has provided by way of non-limiting examples a full and informative description of the exemplary embodiment of this invention. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings of this invention will still fall within the scope of this invention as defined in the appended claims. Indeed there is a further embodiment comprising a combination of one or more embodiments with any of the other embodiments previously discussed.

Claims

1 . An apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to:

determine at least one dynamic transmission parameter;

provide an individual transmitter antenna configuration selection within a multiple-input multiple-output antenna array based on the at least one dynamic transmission parameter; and

implement the individual antenna configuration selection within a multiple-input multiple-output antenna array by control of at least one power amplifier and/or at least one power divider located before each antenna element.

2. The apparatus as claimed in claim 1 , wherein apparatus caused to determine at least one dynamic transmission parameter is caused to determine at least one of: a number of user equipment the apparatus is in communication with;

a user demand parameter;

locations of user equipment the apparatus is in communication with;

a defined transmission power;

an average transmitted power in one direction during a specified time interval; a time;

a date; and

a mode of operation defining in which massive multiple-input multiple-output mode the apparatus is operating.

3. The apparatus as claimed in any of claims 1 and 2, wherein the apparatus caused to provide an individual transmitter antenna configuration selection within a multiple-input multiple-output antenna array based on the at least one dynamic transmission parameter is caused to perform at least one of:

provide individual transmitter antenna configuration selections within a multiple- input multiple-output antenna array on an antenna element by element basis within an antenna sub-panel; provide individual transmitter antenna configuration selections within a multiple- input multiple-output antenna array on an antenna sub-panel by sub-panel basis; provide individual transmitter antenna configuration selections within a multiple- input multiple-output antenna array on an antenna element polarisation by antenna element polarisation basis.

4. The apparatus as claimed in any of claims 1 to 3, wherein the apparatus caused to implement the individual antenna configuration selection within a multiple-input multiple-output antenna array by control of at least one power amplifiers and/or at least one power divider located before each antenna element is caused to perform at least one of:

control at least one switch coupling a power input for the at least one power amplifier to a power supply unit;

control at least one power supply unit coupled to at least one power amplifier; control the at least one power divider configured to selectively couple an output from the at least one power amplifier to antenna elements; and

control at least one power divider of the at least one power dividers configured to selectively couple an output from the at least one power amplifier to at least one further power divider of the at least one power divider and control the at least one further power divider configured to selectively couple the output from the at least one power amplifier to the antenna elements.

5. The apparatus as claimed in any of claims 1 to 4, wherein the apparatus caused to provide an individual transmitter antenna configuration selection within a multiple- input multiple-output antenna array based on the at least one dynamic transmission parameter is caused to:

measure a channel between the apparatus and at least one further apparatus based on at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array;

determine at least one performance parameter associated with the measured channel for the at least two candidate individual transmitter antenna configurations; select one of the at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array based on the at least one performance parameter; and

check whether the selected one of the at least two candidate individual transmitter antenna configurations meet or exceed a determined performance requirement.

6. The apparatus as claimed in claim 5, wherein the apparatus caused to measure a channel between the apparatus and at least one further apparatus based on at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array is caused to perform at least one of:

measure uplink sounding in a full digital array time division duplex apparatus; measure downlink reference signal and channel state indication feedback in a full digital array frequency division duplex apparatus;

measure downlink reference signal and channel state indication feedback in a full digital array time division duplex apparatus;

measure uplink sounding for different sub-panel configurations in a hybrid array time division duplex apparatus;

measure downlink reference signal and channel state indication feedback for different sub-panel configurations in a hybrid array frequency division duplex apparatus; and

measure downlink reference signal and channel state indication feedback for different sub-panel configurations in a hybrid array time division duplex apparatus.

7. The apparatus as claimed in any of claims 5 and 6, further caused to:

measure a channel between the apparatus and at least one further apparatus based on the at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array;

calculate downlink channel covariance matrices out of estimated downlink channel matrices; and

wherein the apparatus caused to select one of the at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array based on the at least one performance parameter is caused to perform at least one of:

select highly correlated antenna elements to be switched off;

select antenna elements based on an angular spread deduced in one or more different geometrical dimensions, the deduced angular spread defining one or more dimensions along which a number of antenna elements to be switched off is selected; and

select antenna elements based on a spatial covariance/correlation of antenna elements in a separate horizontal and vertical directions.

8. The apparatus as claimed in any of claims 1 to 7, wherein the apparatus caused to provide an individual transmitter antenna configuration selection within a multiple- input multiple-output antenna array based on the at least one dynamic transmission parameter is caused to optimize a function of weighted sum of the at least one dynamic transmission parameter and a total required power consumption and determine at least one dynamic transmission parameter based on a selection of a set of the further apparatus out of the set of all active further apparatus and a selection of a set of antenna elements out of the set of all antenna elements within the multiple-input multiple-output antenna array.

9. The apparatus as claimed in any of claims 5 to 8, wherein the apparatus caused to measure a channel between the apparatus and at least one further apparatus based on at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array is caused to measure a uplink channel between the apparatus and at least one further apparatus using all antenna elements within the multiple-input multiple-output antenna array as receiver antennas, and wherein the apparatus caused to select one of the at least two configurations within the multiple input multiple output antenna array based on the at least one performance parameter is caused to calculate one or more downlink candidate individual transmitter antenna configuration selections based on the measured uplink channel.

10. A method comprising:

determining at least one dynamic transmission parameter; providing an individual transmitter antenna configuration selection within a multiple-input multiple-output antenna array associated with an apparatus based on the at least one dynamic transmission parameter; and

implementing the individual antenna configuration selection within a multiple- input multiple-output antenna array by control of at least one power amplifier and/or at least one power divider located before each antenna element.

1 1 . The method as claimed in claim 10, wherein determining at least one dynamic transmission parameter comprises at least one of:

a number of user equipment the apparatus is in communication with;

a user demand parameter;

locations of user equipment the apparatus is in communication with a defined transmission power;

a date; and

12. The method as claimed in any of claims 10 and 1 1 , wherein providing an individual transmitter antenna configuration selection within a multiple-input multiple- output antenna array based on the at least one dynamic transmission parameter comprises at least one of:

providing individual transmitter antenna configuration selections within a multiple-input multiple-output antenna array on an antenna element by element basis within an antenna sub-panel;

providing individual transmitter antenna configuration selections within a multiple-input multiple-output antenna array on an antenna sub-panel by sub-panel basis; and

providing individual transmitter antenna configuration selections within a multiple-input multiple-output antenna array on an antenna element polarisation by antenna element polarisation basis.

13. The method as claimed in any of claims 10 to 12, wherein implementing the individual antenna configuration selection within a multiple-input multiple-output antenna array by control of at least one power amplifiers and/or at least one power divider located before each antenna element comprises at least one of:

controlling at least one switch coupling a power input for the at least one power amplifier to a power supply unit;

controlling at least one power supply unit coupled to at least one power amplifier;

controlling the at least one power divider configured to selectively couple an output from the at least one power amplifier to antenna elements; and

controlling at least one power divider of the at least one power dividers configured to selectively couple an output from the at least one power amplifier to at least one further power divider of the at least one power divider and control the at least one further power divider configured to selectively couple the output from the at least one power amplifier to the antenna elements.

14. The method as claimed in any of claims 10 to 13, wherein providing an individual transmitter antenna configuration selection within a multiple-input multiple- output antenna array based on the at least one dynamic transmission parameter comprises:

measuring a channel between the apparatus and at least one further apparatus based on at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array;

determining at least one performance parameter associated with the measured channel for the at least two candidate individual transmitter antenna configurations; selecting one of the at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array based on the at least one performance parameter; and

checking whether the selected one of the at least two candidate individual transmitter antenna configurations meet or exceed a determined performance requirement.

15. The method as claimed in claim 14, wherein measuring a channel between the apparatus and at least one further apparatus based on at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array comprises at least one of:

measuring uplink sounding in a full digital array time division duplex apparatus; measuring downlink reference signal and channel state indication feedback in a full digital array frequency division duplex apparatus;

measuring downlink reference signal and channel state indication feedback in a full digital array time division duplex apparatus;

measuring uplink sounding for different sub-panel configurations in a hybrid array time division duplex apparatus;

measuring downlink reference signal and channel state indication feedback for different sub-panel configurations in a hybrid array frequency division duplex apparatus; and

measuring downlink reference signal and channel state indication feedback for different sub-panel configurations in a hybrid array time division duplex apparatus.

16. The method as claimed in any of claims 14 and 15, further comprising:

measuring a channel between the apparatus and at least one further apparatus based on the at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array;

calculating downlink channel covariance matrices out of estimated downlink channel matrices; and

wherein selecting one of the at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array based on the at least one performance parameter comprises at least one of:

selecting highly correlated antenna elements to be switched off;

selecting antenna elements based on an angular spread deduced in one or more different geometrical dimensions, the deduced angular spread defining one or more dimensions along which a number of antenna elements to be switched off is selected; and

selecting antenna elements based on a spatial covariance/correlation of antenna elements in a separate horizontal and vertical directions.

17. The method as claimed in any of claims 10 to 16, wherein providing an individual transmitter antenna configuration selection within a multiple-input multiple- output antenna array based on the at least one dynamic transmission parameter comprises optimizing a function of weighted sum of the at least one dynamic transmission parameter and a total required power consumption and determine at least one dynamic transmission parameter based on a selection of a set of the further apparatus out of the set of all active further apparatus and a selection of a set of antenna elements out of the set of all antenna elements within the multiple-input multiple-output antenna array.

18. The method as claimed in any of claims 14 to 17, measuring a channel between the apparatus and at least one further apparatus based on at least two candidate individual transmitter antenna configurations within the multiple-input multiple-output antenna array comprises measuring a uplink channel between the apparatus and at least one further apparatus using all antenna elements within the multiple-input multiple-output antenna array as receiver antennas, and wherein selecting one of the at least two configurations within the multiple input multiple output antenna array based on the at least one performance parameter comprises calculating one or more downlink candidate individual transmitter antenna configuration selections based on the measured uplink channel.

19. An apparatus comprising means for:

determining at least one dynamic transmission parameter;

providing an individual transmitter antenna configuration selection within a multiple-input multiple-output antenna array associated with the apparatus based on the at least one dynamic transmission parameter; and

20. The apparatus as claimed in claim 19, wherein the at least one dynamic transmission parameter comprises at least one of: a number of user equipment the apparatus is in communication with;

a user demand parameter;

a date; and