Patent Publication Number: US-2023132552-A1

Title: Full duplex

Description:
TECHNOLOGICAL FIELD 
     Embodiments of the present disclosure relate to controlling full duplex communication. 
     BACKGROUND 
     Full duplex (FD) operation occurs when a radio transceiver simultaneously transmits and receives radio waves with overlapping frequencies. The transmission path leaks energy to the reception path causing self-interference and a transmitted signal can generate interference in a received signal. 
     A Physical Resource Block (PRB) is the smallest time-frequency tile that can be allocated as a resource for a radio transceiver. For example, in an orthogonal frequency division (OFDM) implementation, a PRB can be defined as consisting of a fixed number of consecutive subcarriers for one time slot. For example, 12 consecutive subcarriers for one time slot of duration 0.5 ms. Full duplex operation occurs when a radio transceiver simultaneously transmits and receives radio waves in the same PRB. 
     It would be desirable to reduce or control self-interference during full duplex operation of a transceiver. 
     BRIEF SUMMARY 
     According to various, but not necessarily all, embodiments there is provided an apparatus comprising:
         radio frequency paths for antenna elements of an array of antenna elements; and means for:   determining which of a first group of radio frequency paths are transmission radio frequency paths to be used for transmission and which of a second group of radio frequency paths are reception radio frequency paths to be used for reception; and   controlling when to use the determined transmission radio frequency paths for transmission and the determined reception radio frequency paths for reception.       

     In some but not necessarily all examples, the array of antenna elements is a one or two-dimensional array of antenna elements that is positioned on a single surface or a single edge of the apparatus. 
     In some but not necessarily all examples, the apparatus comprises control means for enabling full duplex operation of the apparatus comprising simultaneously using the determined transmission radio frequency paths for transmission in at least a first frequency range and the determined reception radio frequency paths for reception in at least the first frequency range. 
     In some but not necessarily all examples, the apparatus comprises means for switching between a time division duplex mode of operation in which radio frequency paths are not used simultaneously for transmission and reception and a full duplex mode of operation in which there is simultaneous use of the determined transmission radio frequency paths for transmission in at least a first frequency range and the determined reception radio frequency paths for reception in at least the first frequency range. 
     In some but not necessarily all examples, each of at least a first plurality of the antenna elements have a pair of parallel radio frequency paths comprising one radio frequency path for transmission and another radio frequency path for reception. 
     In some but not necessarily all examples, the apparatus comprises at least one first switching means for selecting one or more of the radio frequency paths for transmission to be used as transmission radio frequency paths and at least one second switching means for selecting one or more of the radio frequency paths for reception to be used as reception radio frequency paths. 
     In some but not necessarily all examples, each radio frequency path for transmission and each radio frequency path for reception has a separate phase shifter. 
     In some but not necessarily all examples, the first group of radio frequency paths provides a single radio frequency path, for transmission, to each antenna element in a first sub-set of the antenna elements and wherein the second group of radio frequency paths provides a single radio frequency path, for reception, to each antenna element in a second sub-set of the antenna elements, wherein the first sub-set and the second sub-set fully or partially overlap. 
     In some but not necessarily all examples, the first group of radio frequency paths provides a single radio frequency path, for transmission, to each antenna element in a first sub-set of the antenna elements and wherein the second group of radio frequency paths provides a single radio frequency path, for reception, to each antenna element in a second sub-set of the antenna elements, wherein the first sub-set and the second sub-set do not overlap. 
     In some but not necessarily all examples, the apparatus comprises control means for controlling the radio frequency paths to each antenna element such that each antenna element is configured to transmit, configured to receive or configured for non-use. 
     In some but not necessarily all examples, the control means for controlling the radio frequency paths to each antenna element comprises means for terminating at least one radio frequency path for reception at a known state. 
     In some but not necessarily all examples, the termination of the at least one radio frequency path for reception path to a known state is either a direct termination, an indirect termination via a phase shifter, or an indirect termination via a serially connected phase shifter and amplifier. 
     In some but not necessarily all examples, the apparatus comprises control means for controlling phase shifts in at least some of the radio frequency paths for antenna elements; control means for optimizing phase shifts in the transmission radio frequency paths to optimize isolation of the reception radio frequency paths; and control means for optimizing phase shifts in the reception radio frequency paths to optimize a combined isolation of the reception radio frequency paths. 
     In some but not necessarily all examples, the apparatus comprises control means for controlling phase shifts in at least some of the radio frequency paths for antenna elements to achieve a preferred beam forming direction; control means for optimizing phase shifts in the transmission radio frequency paths to optimize isolation of the reception radio frequency paths; and control means for optimizing phase shifts in the reception radio frequency paths to optimize a combined isolation of the reception radio frequency paths. 
     In some but not necessarily all examples, the apparatus is a portable electronic device. 
     In some but not necessarily all examples, there is provided a system comprising a network node and at least one apparatus, wherein the apparatus is a mobile equipment, wherein transmission is uplink transmission to the network node and reception is downlink reception from the network node, wherein the apparatus and the network node have a relative position defined by a beam steering angle, wherein the system is configured to enable communication between the network node and the apparatus to be used in the determination of the transmission radio frequency paths and the reception radio frequency paths and/or controlling when to use the determined transmission radio frequency paths for transmission and the determined reception radio frequency paths for reception. 
     In some but not necessarily all examples, the communication between the network node and the apparatus is used to determine a maximum uplink power for the beam steering angle, wherein the maximum uplink power, for a given beam steering angle is dependent upon a beam steering angle-dependent isolation function, gain loss at the mobile equipment, and a downlink sensitivity limit. 
     In some but not necessarily all examples, there is provided a method comprising:
         determining which of a first group of radio frequency paths for antenna elements of an array of antenna elements are transmission radio frequency paths to be used for transmission and which of a second group of radio frequency paths are reception radio frequency paths to be used for reception; and   controlling when to use the determined transmission radio frequency paths for transmission and the determined reception radio frequency paths for reception.       

     In some but not necessarily all examples, there is provided a computer program that, when run on a computer, performs:
         determining which of a first group of radio frequency paths for antenna elements of an array of antenna elements are transmission radio frequency paths to be used for transmission and which of a second group of radio frequency paths are reception radio frequency paths to be used for reception; and   controlling when to use the determined transmission radio frequency paths for transmission and the determined reception radio frequency paths for reception.       

     According to various, but not necessarily all, embodiments there is provided examples as claimed in the appended claims. 
    
    
     
       BRIEF DESCRIPTION 
       Some examples will now be described with reference to the accompanying drawings in which: 
         FIG.  1    shows an example of the subject matter described herein; 
         FIG.  2 A,  2 B,  2 C,  2 D  show examples of the subject matter described herein; 
         FIG.  3    shows another example of the subject matter described herein; 
         FIG.  4 A,  4 B  show examples of the subject matter described herein; 
         FIG.  5 A  shows another example of the subject matter described herein; 
         FIG.  5 B  shows another example of the subject matter described herein; 
         FIG.  6    shows another example of the subject matter described herein; 
         FIG.  7 A  shows another example of the subject matter described herein; 
         FIG.  7 B  shows another example of the subject matter described herein; 
         FIG.  8 A  shows another example of the subject matter described herein; 
         FIG.  8 B  shows another example of the subject matter described herein; 
         FIG.  9    shows another example of the subject matter described herein; 
         FIG.  10    shows another example of the subject matter described herein; 
         FIG.  11    shows another example of the subject matter described herein; and 
         FIG.  12    shows another example of the subject matter described herein. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will be made in the FIGS and the following examples to an apparatus  10  comprising: 
     radio frequency paths  20  for antenna elements  12  of an array  14  of antenna elements  12 ; and means  50  for: determining which of a first group  22  of radio frequency paths  20  are transmission radio frequency paths  20  to be used for transmission and which of a second group  24  of radio frequency paths  20  are reception radio frequency paths  20  to be used for reception; and controlling when to use the determined transmission radio frequency paths  20  for transmission and the determined reception radio frequency paths  20  for reception. 
     The apparatus  10  enables a flexible operation. The apparatus  10  can operate in full duplex mode. The full duplex mode can also be flexible, in at least some examples, if required. The size of the allocated time-frequency tile used for full duplex can, in at least some examples be controlled. For example, the duration of the time-frequency tile used for full duplex can be controlled and/or the frequency range of the time-frequency tile used for full duplex can be controlled. 
     The apparatus  10  can in some examples, flexibly operate in modes other than or in addition to full duplex, for example, time division duplex (TDD) mode and/or frequency division duplex (FDD) mode. 
     The apparatus  10  by selection of which of the first group  22  of radio frequency paths  20  are transmission radio frequency paths  20  and which of the second group  24  of radio frequency paths  20  are reception radio frequency paths  20  during full duplex operation (simultaneous use, at overlapping frequency ranges, for transmission and reception), controls isolation between the reception radio frequency paths  20  to transmitter  40  and the transmission radio frequency paths  20  to receiver  42 . 
     In some examples, the reception radio frequency paths  20  are physically separated from transmission radio frequency paths  20  by one or more radio frequency paths  20  that are not in use for transmission or reception. 
     The apparatus  10  can, in some examples, flexibly switch into or out of the full duplex mode of operation. In some examples, the switch  30  can be dependent upon a reception quality parameter measured at the apparatus  10 . 
       FIG.  1    illustrates an example of the apparatus  10 . 
     The apparatus  10  comprises radio frequency paths  20  for antenna elements  12  of an array  14  of antenna elements  12 . 
     A first group  22  of radio frequency paths  20  are suitable for use as transmission radio frequency paths in that each path  20  is capable of interconnecting a respective antenna element  12  with a transmitter  40 . When a radio frequency path  20  is interconnected to the transmitter  40  it is referred to as a transmission radio frequency path  20  rather than a radio frequency path  20 . 
     A second group  24  of radio frequency paths  20  are suitable for use as reception radio frequency paths in that each path  20  is capable of interconnecting a respective antenna element  12  with a receiver  42 . When a radio frequency path  20  is interconnected to the receiver  42  it is referred to as a reception radio frequency path  20  rather than a radio frequency path  20 . 
     Each antenna element  12  cannot be simultaneously connected to both the transmitter  40  and the receiver  42 . That is a radio frequency path  20  cannot be simultaneously both a reception radio frequency path  20  and a transmission radio frequency path  20 . 
     In this example, at least some of the antenna elements  12  can operate as a reception radio frequency path  20  or a transmission radio frequency path  20 . Switches  30  can be used to control whether a particular antenna element  12  operates as a reception radio frequency path  20  or a transmission radio frequency path  20 . 
     The apparatus comprises a controller  50  configured to determine which of the first group  22  of radio frequency paths  20  are transmission radio frequency paths  20  to be used for transmission and which of a second group  24  of radio frequency paths  20  are reception radio frequency paths  20  to be used for reception. In the example illustrated the controller  50  provides control signals to the switches  30  which select whether a particular antenna element  12  operates as a reception radio frequency path  20  or a transmission radio frequency path  20 . 
     As will be described later it is also possible for the controller  50  to provide control signals to the switches  30  which select whether a particular antenna element  12  operates as a reception radio frequency path  20 , a transmission radio frequency path  20  or is not used. 
     The apparatus controller  50  is also configured to control when to use the determined transmission radio frequency paths  20  for transmission and the determined reception radio frequency paths  20  for reception. This can, for example, be controlled by the timing of the control signals. 
     The controller  50  can be implemented in many ways as will be described later. 
     In this example, each of a first plurality of the antenna elements  12  have a pair of parallel radio frequency paths  20  comprising one radio frequency path  20  for transmission and another radio frequency path  20  for reception. A first switching means  30 _ 1  is configured to select, under control of the controller  50 , the radio frequency path  20  for transmission to be used as a transmission radio frequency path  20 . A second switching means  30 _ 2  is configured to select, under control of the controller  50 , the radio frequency path  20  for reception to be used as a reception radio frequency path  20 . 
     The illustrated apparatus  10  therefore comprises: 
     radio frequency paths  20  for antenna elements  12  of an array  14  of antenna elements  12 ; and means  50  for: determining which of a first group  22  of radio frequency paths  20  are transmission radio frequency paths  20  to be used for transmission and which of a second group  24  of radio frequency paths  20  are reception radio frequency paths  20  to be used for reception; and controlling when to use the determined transmission radio frequency paths  20  for transmission and the determined reception radio frequency paths  20  for reception. 
     The apparatus  10  enables a flexible operation. The apparatus  10  can operate in full duplex mode-simultaneous transmission and reception using overlapping frequency ranges. The full duplex mode is also flexible, if required. The size of the allocated time-frequency tile used for full duplex can, in at least some examples be controlled. For example, the duration of the time-frequency tile used for full duplex can be controlled and/or the frequency range of the time-frequency tile used for full duplex can be controlled. 
     The apparatus by selection of which of the first group  22  of radio frequency paths  20  are transmission radio frequency paths  20  and which of the second group of radio frequency paths  20  are reception radio frequency paths  20  during full duplex operation (simultaneous use, at overlapping frequency ranges, for transmission and reception) controls isolation between the reception radio frequency paths  20  to receiver  42  and the transmission radio frequency paths  20  to transmitter  40 . 
     In the example illustrated, the array  14  of antenna elements  12  is illustrated as a one dimensional array. However, the array can for example have other arrangements. It may, for example, be a two-dimensional array  14 . 
     It should be appreciated that in some examples the transmitter  40  can be configured to send the same information for transmission via each transmission radio frequency path  20 . In other examples, the transmitter  40  can be configured to send different information for transmission via different ones or groups of transmission radio frequency paths  20 . 
     It should be appreciated that in some examples the receiver  42  can be configured to receive the same information via each reception radio frequency path  20 . In other examples, the receiver  42  can be configured to receive the different information via different ones or groups of reception radio frequency paths  20 . 
       FIG.  2 A  illustrates an example of a time division duplex mode of operation.  FIG.  2 B  illustrates an example of a frequency division duplex mode of operation.  FIG.  2 C  illustrates an example of a full duplex mode of operation.  FIG.  2 D  illustrates another example of a full duplex mode of operation. 
       FIG.  2 A  illustrates an example of a time division duplex (TDD) mode of operation. 
     The transmission allocation (transmission time-frequency tile Tx) and the reception allocation (reception time-frequency tile Tx), are separated—they are separated in time (no overlap) and overlap in frequency. In this example, the overlap in frequency is exact. No frequency-time slots (PRB) are shared for transmission and reception. All antenna elements  12  can be used for transmission. All antenna elements can be used for reception. There is no need to divide the antenna elements  12  between transmission and reception. 
     In some but not necessarily all examples, the apparatus  10  can implement the TDD mode by using determined radio frequency paths  20  of the first group  22  of radio frequency paths  20  for transmission at a first time and using determined radio frequency paths  20  of the second group  24  of radio frequency paths  20  for reception at a second time different to the first time. The first group  22  of radio frequency paths  20  for transmission and the second group  24  of radio frequency paths  20  for reception can fully overlap in frequency in this TDD mode. 
       FIG.  2 B  illustrates an example of a frequency division duplex (FDD) mode of operation. 
     The transmission allocation (transmission time-frequency tile Tx) and the reception allocation (reception time-frequency tile Rx) are separated—they are separated in frequency (no overlap) and overlap in time. In this example, the overlap in time is exact. No frequency-time slots (PRB) are shared for transmission and reception. 
     In some but not necessarily all examples, the apparatus  10  can implement a FDD mode by using determined radio frequency paths  20  of the first group  22  of radio frequency paths  20  for transmission at a first time using a first frequency range and determined radio frequency paths  20  of the second group  24  of radio frequency paths  20  for reception at the first time using a second frequency range that is different to and does not overlap the first frequency range. The first group  22  of radio frequency paths  20  for transmission and the second group  24  of radio frequency paths  20  for reception can fully overlap in time in this FDD mode. 
       FIG.  2 C and  2 D  illustrate examples of a full duplex (FD) mode of operation. The transmission allocation (transmission time-frequency tile Tx) and the reception allocation (reception time-frequency tile Rx) are not separated and they overlap—they overlap in frequency and overlap in time. There is simultaneous transmission and reception within the same frequency range. Frequency-time tiles (PRB) are shared for transmission and reception. Separation of transmission and reception channels is via selection of different antenna elements  12  for transmission and reception. In the example of  FIG.  2 C  the overlap in time and frequency is exact. In the example of  FIG.  2 D  the overlap in time and frequency is not exact. 
     The apparatus  10  in at least some examples comprises controller  50  for enabling full duplex operation of the apparatus  10 . Full duplex operation comprises simultaneously using the determined transmission radio frequency paths  20  for transmission in at least a first frequency range and the determined reception radio frequency paths  20  for reception in at least the first frequency range. 
     During full duplex operation, transmission and reception are simultaneous and different antenna elements  12  are used for transmission and reception. A first set of the first group  22  of radio frequency paths  20  are used as transmission radio frequency paths. A second set of the second group  22  of radio frequency paths  20  are used as reception radio frequency paths. 
     It will be appreciated that in  FIG.  2 D  the operational mode is full duplex but additionally comprises a partial TDD mode (some but not all allocated resources are time separated with partial frequency overlap) and comprises a partial FDD mode (some but not all allocated resources are frequency separated with partial time overlap) 
     The controller  50  can in some examples, flexibly operate the apparatus  10  in modes other than or in addition to full duplex, for example, time division duplex mode and/or frequency division duplex mode. 
     The controller  50  can control switching to and/or from the full duplex mode of operation. In some examples, the switch can be dependent upon a reception quality parameter measured at the apparatus  10 . 
     In particular a switch from the full duplex mode of operation to the time division duplex mode of operation can occur when a reception quality parameter measured at the apparatus falls below a threshold value. 
     The FD mode does not use all antenna elements  12  for reception, however, the TDD mode uses more, for example all, antenna elements  12  for reception. The TDD mode is therefore expected to have improved gain. The same antenna elements  12  are used for TDD mode of operation and FD mode of operation, however, in FD mode some of the antenna elements  12  are simultaneously used for transmission while others are used for reception, whereas in TDD mode at one time all the antenna elements  12  are simultaneously used for transmission while at another time all the antenna elements  12  are simultaneously used for reception. 
     The reception quality parameter can, for example, fall below the threshold because of reception gain loss, or increased self-interference (e.g. isolation reduction and/or increased uplink transmit power). 
     The controller  50  is configured to control switching between a time division duplex mode of operation in which radio frequency paths  20  are not used simultaneously for transmission and reception and a full duplex mode of operation in which there is simultaneous use of the determined transmission radio frequency paths  20  for transmission in at least a first frequency range and the determined reception radio frequency paths  20  for reception in at least the first frequency range. 
       FIG.  3    illustrates an example of the apparatus  10 . The FIG illustrates the array  14  of antenna elements  12 . 
     The array  14  of antenna elements  12  in this and other examples is a single array. The antenna elements are operationally contiguous—the separation distance between nearest neighbor antenna elements  12  within the array  14  is less than the wavelength at the minimum operational frequency of the antenna elements  12  used by the apparatus  10 . An antenna array (or array antenna) is a set of multiple connected antennas which work together as a single antenna, to transmit and/or receive radio waves. A first set of elements can be combined as a first sub-array to transmit a first radio wave signal, while a second set of elements can be combined as a second sub-array to simultaneously receive a second radio wave signal. 
     In some but nnot necessarily all examples, the array  14  of antenna elements  12  is positioned on a single surface of the apparatus  10  (or an edge of the apparatus  10 ). 
     The array  14  of antenna elements  12  can be a one or two-dimensional array  14  of antenna elements  12 , for example. 
       FIG.  4 A and  4 B  illustrate an example in which the array  14  of antenna elements  12  is a one-dimensional array  14  of antenna elements  12 , positioned along a surface/edge/side of a electronic communications device  10  such as a hand-portable apparatus  10 . The apparatus can, for example, be a mobile phone, a smartphone, a tablet computer, a laptop, a watch, a wearable device etc. 
     In  FIG.  4 A  the antenna elements  12  are divided into two categories only—those antenna elements  12   T  to be used for transmission by transmission radio frequency paths  20  (not illustrated in this FIG) and those antenna elements  12   R  to be used for reception by reception radio frequency paths  20  (not illustrated in this FIG). 
     In  FIG.  4 B  the antenna elements  12  are divided into three categories only—those antenna elements  12   T  to be used for transmission by transmission radio frequency paths  20  (not illustrated in this FIG), those antenna elements  12   R  to be used for reception by reception radio frequency paths  20  (not illustrated in this FIG), and those antenna elements  12   1 that are configured for non-use. 
     The one or more antenna elements  12   I  configured for non-use physically separate the antenna elements  12   T  to be used for transmission by transmission radio frequency paths  20 , and the antenna elements  12   R  to be used for reception by reception radio frequency paths  20 . This increases isolation between the transmission radio frequency paths  20  and the reception radio frequency paths  20 . 
     In some but not necessarily all examples, the controller  50  (not illustrated in this FIG) is configured to control the radio frequency paths  20  to a set of antenna elements  12  such that each antenna element  12  in the set is configured to transmit  12   T , configured to receive  12   R  or configured for non-use  12   I . 
       FIG.  5 A  illustrates an example of a controller  50 . Implementation of a controller  50  may be as controller circuitry. The controller  50  may be implemented in hardware alone, have certain aspects in software including firmware alone or can be a combination of hardware and software (including firmware). 
     As illustrated in  FIG.  5 A  the controller  50  may be implemented using instructions that enable hardware functionality, for example, by using executable instructions of a computer program  66  in a general-purpose or special-purpose processor  62  that may be stored on a computer readable storage medium (disk, memory etc) to be executed by such a processor  62 . 
     The processor  62  is configured to read from and write to the memory  64 . The processor  62  may also comprise an output interface via which data and/or commands are output by the processor  62  and an input interface via which data and/or commands are input to the processor  62 . 
     The memory  64  stores a computer program  66  comprising computer program instructions (computer program code) that controls the operation of the apparatus  10  when loaded into the processor  62 . The computer program instructions, of the computer program  66 , provide the logic and routines that enables the apparatus to perform the methods illustrated in  FIGS.  6   . The processor  62  by reading the memory  64  is able to load and execute the computer program  66 . 
     The apparatus  10  therefore comprises: 
     at least one processor  62 ; and 
     at least one memory  64  including computer program code  66   
     the at least one memory  64  and the computer program code  66  configured to, with 
     the at least one processor  62 , cause the apparatus  10  at least to perform:
         determining which of a first group  22  of radio frequency paths  20  for antenna elements  12  of an array  14  of antenna elements  12  are transmission radio frequency paths  20  to be used for transmission and which of a second group  24  of radio frequency paths  20  are reception radio frequency paths  20  to be used for reception; and   controlling when to use the determined transmission radio frequency paths  20  for transmission and the determined reception radio frequency paths  20  for reception.       

     As illustrated in  FIG.  5 B , the computer program  66  may arrive at the apparatus  10  via any suitable delivery mechanism  68 . The delivery mechanism  68  may be, for example, a machine readable medium, a computer-readable medium, a non-transitory computer-readable storage medium, a computer program product, a memory device, a record medium such as a Compact Disc Read-Only Memory (CD-ROM) or a Digital Versatile Disc (DVD) or a solid state memory, an article of manufacture that comprises or tangibly embodies the computer program  66 . The delivery mechanism may be a signal configured to reliably transfer the computer program  66 . The apparatus  10  may propagate or transmit the computer program  66  as a computer data signal. 
     Computer program instructions for causing an apparatus to perform at least the following or for performing at least the following:
         determining which of a first group  22  of radio frequency paths  20  for antenna elements  12  of an array  14  of antenna elements  12  are transmission radio frequency paths  20  to be used for transmission and which of a second group  24  of radio frequency paths  20  are reception radio frequency paths  20  to be used for reception; and   controlling when to use the determined transmission radio frequency paths  20  for transmission and the determined reception radio frequency paths  20  for reception.       

     The computer program instructions may be comprised in a computer program, a non-transitory computer readable medium, a computer program product, a machine readable medium. In some but not necessarily all examples, the computer program instructions may be distributed over more than one computer program. 
     Although the memory  64  is illustrated as a single component/circuitry it may be implemented as one or more separate components/circuitry some or all of which may be integrated/removable and/or may provide permanent/semi-permanent/dynamic/cached storage. 
     Although the processor  62  is illustrated as a single component/circuitry it may be implemented as one or more separate components/circuitry some or all of which may be integrated/removable. The processor  62  may be a single core or multi-core processor. 
     References to ‘computer-readable storage medium’, ‘computer program product’, ‘tangibly embodied computer program’ etc. or a ‘controller’, ‘computer’, ‘processor’ etc. should be understood to encompass not only computers having different architectures such as single/multi-processor architectures and sequential (Von Neumann)/parallel architectures but also specialized circuits such as field-programmable gate arrays (FPGA), application specific circuits (ASIC), signal processing devices and other processing circuitry. References to computer program, instructions, code etc. should be understood to encompass software for a programmable processor or firmware such as, for example, the programmable content of a hardware device whether instructions for a processor, or configuration settings for a fixed-function device, gate array or programmable logic device etc. 
     As used in this application, the term ‘circuitry’ may refer to one or more or all of the following: 
     (a) hardware-only circuitry implementations (such as implementations in only analog and/or digital circuitry) and 
     (b) combinations of hardware circuits and software, such as (as applicable): 
     (i) a combination of analog and/or digital hardware circuit(s) with software/firmware and 
     (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions and 
     (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g. firmware) for operation, but the software may not be present when it is not needed for operation. 
     This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit for a mobile device or a similar integrated circuit in a server, a cellular network device, or other computing or network device. 
     The blocks illustrated in the  FIGS.  6    may represent steps in a method and/or sections of code in the computer program  66 . The illustration of a particular order to the blocks does not necessarily imply that there is a required or preferred order for the blocks and the order and arrangement of the block may be varied. Furthermore, it may be possible for some blocks to be omitted. 
       FIG.  6    illustrates an example of a method  90 . The method  90  comprises: 
     at block  92 , determining which of a first group  22  of radio frequency paths  20  for antenna elements  12  of an array  14  of antenna elements  12  are transmission radio frequency paths  20  to be used for transmission and which of a second group  24  of radio frequency paths  20  are reception radio frequency paths  20  to be used for reception; and 
     at block  94 , controlling when to use the determined transmission radio frequency paths  20  for transmission and the determined reception radio frequency paths  20  for reception. 
     The method  90  can be augmented as described in the examples provided in this description in relation to the apparatus  10 . 
     The examples illustrated in  FIG.  7 A,  7 B,  8 A,  8 B  are apparatus  10  as previously described. 
     The apparatus  10  comprise radio frequency paths  20  for antenna elements  12  of an array  14  of antenna elements  12 . 
     A first group  22  of radio frequency paths  20  are suitable for use as transmission radio frequency paths in that each path  20  is capable of interconnecting a respective antenna element  12  with a transmitter  40  (not illustrated in these FIGS). When a radio frequency path  20  is interconnected to the transmitter  40  it is referred to as a transmission radio frequency path  20   T  rather than a radio frequency path  20 . 
     A second group  24  of radio frequency paths  20  are suitable for use as reception radio frequency paths in that each path  20  is capable of interconnecting a respective antenna element  12  with a receiver  42  (not illustrated in these FIGS). When a radio frequency path  20  is interconnected to the receiver  42  it is referred to as a reception radio frequency path  20   R  rather than a radio frequency path  20 . 
     The first group  22  of radio frequency paths  20  provides a single transmission radio frequency path  20   T  to each antenna element  12  in a first set of the antenna elements  12 . The second group  24  of radio frequency paths  20  provides a single reception radio frequency path  20   R  to each antenna element  12  in a second set of the antenna elements  12 . 
     In the examples of  FIGS.  7 A and  7 B  the first group  22  and the second group  24  fully overlap and comprise all the antenna elements  12 . The first group  22  and the second group  24  are the same. In other examples the groups  22 ,  24  could partially overlap. The first set and the second set are non-intersecting sub-sets of the same group  22 ,  24  of antenna elements  12 . The first set is the top four of the eight antenna elements. The second set is the bottom four of the eight antenna elements. 
     In the examples of  FIGS.  8 A and  8 B  the first group  22  and the second group  24  do not overlap and are distinct. The first group  22  is the top four of the eight antenna elements  12 . The second group  24  is the bottom four of the eight antenna elements  12 . The first set is the first group  22 . The second set is the second group  24 . 
     Each of the antenna elements  12  has a pair of parallel radio frequency paths  20  comprising one radio frequency path  20  for transmission and another radio frequency path  20  for reception. 
     Each radio frequency path  20  for transmission comprises a controllable phase shifter  70 , and also a controllable (transmission) amplifier  72 . 
     Each radio frequency path  20  for reception comprises a controllable phase shifter  70 , and also a controllable (reception) amplifier  72 . 
     Each antenna element  12  cannot be simultaneously connected to both the transmitter  40  and the receiver  42  (not illustrated). That is a radio frequency path  20  cannot be both a reception radio frequency path  20   R  and a transmission radio frequency path  20   T . 
     The antenna elements  12  can operate as part of a reception radio frequency path  20   R  or a transmission radio frequency path  20   T . Switches  30  can be used to control whether a particular antenna element  12  operates as part of a reception radio frequency path  20   R  or part of a transmission radio frequency path  20   T . 
     Each switch  30  selects between the pair of radio frequency paths  20  associated with an antenna element  12 . The collection of switches  30  select the radio frequency paths  20  for transmission to be used as transmission radio frequency paths  20   T  and the radio frequency paths  20  for reception to be used as a reception radio frequency paths  20   R . 
     The apparatus  10  comprises a controller  50  (not illustrated in these FIGS) configured to determine which of the first group  22  of radio frequency paths  20  are transmission radio frequency paths  20   T  to be used for transmission and which of a second group  24  of radio frequency paths  20  are reception radio frequency paths  20   R  to be used for reception. The controller  50  provides control signals to the switches  30  which select whether a particular antenna element  12  operates as part of a reception radio frequency path  20   R  or a transmission radio frequency path  20   T . 
     The apparatus controller  50  is also configured to control when to use the determined transmission radio frequency paths  20   T  for transmission and the determined reception radio frequency paths  20   R  for reception. This can, for example, be controlled by the timing of the control signals. 
     In the examples of  FIG.  7 B,  8 B , the controller  50  is configured to provide control signals to the switches  30  which select whether a particular antenna element  12  operates as a reception radio frequency path  20   R , a transmission radio frequency path  20   T  or is not used for communication. In some examples, the reception radio frequency paths  20   R  are separated from transmission radio frequency paths  20   T  by one or more radio frequency paths  20   I  that are not in use for transmission or reception. 
     The illustrated apparatuses  10  therefore comprise: 
     radio frequency paths  20  for antenna elements  12  of an array  14  of antenna elements  12 ; and means  50  for: determining which of a first group  22  of radio frequency paths  20  are transmission radio frequency paths  20  to be used for transmission and which of a second group  24  of radio frequency paths  20  are reception radio frequency paths  20  to be used for reception; and controlling when to use the determined transmission radio frequency paths  20  for transmission and the determined reception radio frequency paths  20  for reception. 
     In the examples of  FIG.  9   , the controller  50  (not illustrated) is configured to provide control signals to select whether a particular antenna element  12  operates as part of a reception radio frequency path  20   R , a transmission radio frequency path  20   T  or an isolated radio frequency path  20   I  that is not used for communication. The controller  50  is configured to control the radio frequency paths  20  to at least one antenna element  12  such that that the antenna element  12   I  is configured for non-use. This allows the separation of reception radio frequency paths  20   R  from transmission radio frequency paths  20   T  by one or more isolated radio frequency paths  20   I  that are not in use for transmission or reception. 
     The controller  50  is configured to control the radio frequency paths  20  to at least one antenna element  12  such that that the antenna element  12  is isolated (configured for non-use) by terminating (connecting) the antenna element  12  via at least one isolated radio frequency path  20   I  to a known state (for example a fixed impedance such as 50 Ω, open circuit or short circuit). The non-used antenna element  12   I  shown in  FIG.  7 B ,  FIG.  8 B  and  FIG.  9    is shown as terminated to ground (short circuit). 
     The termination of at least one antenna element  12   I  via an isolated radio frequency path  20   I , to a known state is either a direct termination (50 Ω, open circuit or short circuit) ( FIG.  9    III), an indirect termination via the phase shifter  70  ( FIG.  9    II), for example, of a radio frequency path  20  for reception, or an indirect termination ( FIG.  9    I) via the serially connected phase shifter  70  and amplifier  72  of, for example, the radio frequency path  20  for reception. 
     Although the indirect termination is via the phase shifter  70  ( FIG.  9    II) of the radio frequency path  20  for reception, in other examples, the indirect termination is via the phase shifter  70  of the radio frequency path  20  for transmission 
     The antenna element  12   I  configured for non-use is isolated, inactive and is not directly driven. It is not used for transmission or reception, 
     In some examples, the controller  50  can be configured to control the radio frequency paths  20  to at least one antenna element  12  such that that the antenna element  12  is configured for non-use by making the antenna element  12  ‘open circuit’ either directly or indirectly. However, this may be less desirable. The termination of the at least one antenna element  12  to a known voltage, for example ground, allows control of reflections. 
     In some but not necessarily all examples, the controller  50  is configured to control phase shifts applied by the phase shifters  70  in at least some of the radio frequency paths  20 T,  20 R,  20 I for antenna elements  12 . The controller  50  can be configured to vary phase shifts in the transmission radio frequency paths  20 T to optimize isolation of the individual reception radio frequency paths  20 R and then vary phase shifts in the reception radio frequency paths  20 R to optimize a combined isolation of the reception radio frequency paths  20 R. This is done while keeping a main radiation beam in the required angular direction. 
     The isolation of the reception radio frequency paths  20   R  is the transmission power leakage picked up at each reception antenna element  12  compared to the combined transmission power. Isolation is needed to ensure proper linear amplifier operation for all receiving antenna elements  12 . This can be measured during user equipment characterisation, when the apparatus  10  is user equipment. This optimization prevents the reception amplifiers  72  running into compression due to transmission power leakage or causing damage. 
     The combined isolation of the reception radio frequency paths  20   R  is the combined transmission power leakage picked up at all the receiving antenna elements  12  compared to the combined transmission power. Isolation is needed to ensure proper full duplex operation. This can be measured during user equipment characterisation, when the apparatus  10  is user equipment. 
     In some but not necessarily all examples, the controller  50  is configured to control phase shifts in at least some of the radio frequency paths  20  for antenna elements  12  to achieve a preferred beam forming direction for transmission and reception. The controller is configured to then control (relative) phase shifts applied by the phase shifters  70  in at least some of the radio frequency paths  20  for antenna elements  12 . The controller  50  can be configured to vary phase shifts in the transmission radio frequency paths  20   T  to optimize isolation of the reception radio frequency paths  20   R  and then vary phase shifts in the reception radio frequency paths  20   R  to optimize a combined isolation of the reception radio frequency paths  20   R . 
     There can be ranges of different absolute phases for achieving a desired steering direction. It is therefore possible to find phases that achieve the desired steering direction and optimize isolation. 
     A constraint can be that the steering beam direction and the reception steering beam direction cannot deviate by more than a defined threshold. 
     For a particular design of apparatus  10 , the settings of the phase shifters  70  for different beam steering angles and, optionally, the settings for different FD mode configurations can be stored in memory as a look-up table. 
     The FD mode configuration is the selection of which radio frequency paths  20  are transmission radio frequency paths  20   T  and which are reception radio frequency paths  20   R , and, optionally, which are non-use isolated radio frequency paths  20   I . 
     The look-up table can for example associate with each combination of FD mode configuration and beam steering direction, values for identifying the transmission radio frequency paths  20   T , the reception radio frequency paths  20   R  and the isolated radio frequency paths  20   I  (if any) and for identifying the control parameter values for the amplifiers  72  and phase shifters  70  in those paths  20   R ,  20   T ,  20   I . 
       FIG.  10    illustrates an example of a network  100  comprising a plurality of network nodes including terminal nodes  110 , access nodes  120  and one or more core nodes  130 . The terminal nodes  110  and access nodes  120  communicate with each other. The one or more core nodes  130  communicate with the access nodes  120 . 
     The one or more core nodes  130  may, in some examples, communicate with each other. The one or more access nodes  120  may, in some examples, communicate with each other. 
     The network  100  may be a cellular network comprising a plurality of cells  122  each served by an access node  120 . In this example, the interface between the terminal nodes  110  and an access node  120  defining a cell  122  is a wireless interface  124 . 
     The access node  120  is a cellular radio transceiver. The terminal nodes  110  are apparatus  10  comprising cellular radio transceivers. 
     In the example illustrated the cellular network  100  is a third generation Partnership Project (3GPP) network in which the terminal nodes  110  are user equipment (UE) and the access nodes  120  are base stations. 
     In the particular example illustrated the network  100  is a Universal Terrestrial Radio Access network (UTRAN). The UTRAN consists of UTRAN NodeBs  120 , providing the UTRA user plane and control plane (RRC) protocol terminations towards the UE  110 . The NodeBs  120  are interconnected with each other by means of an X2 interface  126 . and are also connected by means of the S1 interface  128  to the Mobility Management Entity (MME)  130 . 
     The term ‘user equipment’ is used to designate mobile equipment comprising a smart card for authentication/encryption etc such as a subscriber identity module (SIM). 
     The NodeB can be any suitable base station. A base station is an access node  120 . It can be a network element in radio access network responsible for radio transmission and reception in one or more cells to or from the user equipment. 
     The UTRAN can be a 3G, 4G or 5G network, for example. It can for example be a New Radio (NR) network that uses gNB as access nodes  120 . New Radio (NR) is the 3GPP name for 5G technology. The apparatus  10 ,  110  can be configured for ultra reliable low latency communication (URLLC) or time sensitive networks (TSN). 
     The cellular network  100  shown in  FIG.  10    could be configured to operate NR in licensed or unlicensed frequency bands. 
     The system  100  therefore comprises a network node  120  and at least one apparatus  10  that operates as a terminal node  110 . The apparatus  10  is a mobile equipment, that operates as user equipment. Transmission by the apparatus  10 ,  110  is uplink transmission to the network node  120  and reception by the apparatus  10 ,  110  is downlink reception from the network node  120 ., 
     The apparatus  10 ,  110  and its serving network node  120  have a relative position defined by a beam steering angle. 
     The system  100  is configured to enable communication between the network node  120  and the apparatus  10 ,  110  to be used in the determination of the transmission radio frequency paths  20   T  and the reception radio frequency paths  20   R  and/or controlling when to use the determined transmission radio frequency paths  20   T  for transmission and the determined reception radio frequency paths  20   R  for reception. 
     The communication between the network node  120  and the apparatus  10 ,  110  can be used to determine a maximum uplink power for the beam steering angle. 
     The apparatus  10 ,  110  is configured to monitor a downlink reception quality parameter, for example, Reference Signal Received Power (RSRP). The downlink reception quality parameter is dependent upon downlink reception gain loss, which depends upon the number of antenna elements  12  used for downlink reception and the beam steering angle. The downlink reception quality parameter is dependent upon uplink transmission interference which is dependent upon isolation and also uplink transmit power. The isolation depends upon the FD mode configuration and also the beam steering angle. 
     If the reception quality parameter falls below a threshold, for example, a downlink sensitivity limit, then the apparatus  10 ,  110  can change operation modes to improve reception. The change can for example be a switch to a different FD mode configuration, for example setting one or more radio frequency paths  20 /antenna elements  12  to ‘non-use’ isolated RF paths  20   I  to improve isolation between the transmission radio frequency paths  20   T  and the reception radio frequency paths  20   R . 
     The change can for example be a switch from full duplex mode, to a TDD mode to increase gain and obviate the need for isolation. 
     The maximum uplink power, for a given beam steering angle is dependent upon a beam steering angle-dependent isolation function, gain loss at the mobile equipment, a downlink sensitivity limit and the uplink power. The uplink power can be controlled to be below a value that, given the isolation, would prevent detection of the downlink signal. 
     The beam steering angle is determined at the apparatus  10 ,  110 . 
     The beam steering angle-dependent isolation function, is particular to the apparatus  10 ,  110  and is preferably stored in the controller  50  of the apparatus  10 ,  110 . 
     The downlink sensitivity limit is defined as the lowest receive power level at which the DL can still be decoded at a given bit error rate. As such for a given DL scenario the UE will measure e.g. RSRP and when above a given limit conclude that it is not at the sensitivity limit. The limit may be defined local to the UE based on characterisation. 
     The gain loss at the mobile equipment  10 ,  110  is, in at least some examples, determined by communication between the network node  120  and the apparatus  10 ,  110 . The network node  120  transmits a reference signal of known power to the apparatus  10 ,  110 . The network node  120  measured the power of the reference signal on reception. The ratio provides the gain loss. 
     It will be appreciated that although communication between the network node  120  and the apparatus  10 ,  110  is required to control the maximum uplink power and/or change the operational mode of the apparatus  10 ,  110 , the decision making function can be located in the network node  120 , in the apparatus  10 ,  110  or split between the network node  120  and the apparatus  10 ,  110 . 
     For example, in some examples, the apparatus  10 ,  110  reports to the network node  120  a real-time value for gain loss at the apparatus  10 ,  110 , and, in at least some examples a real-time isolation value and a downlink sensitivity limit. 
     For example, in other examples, the apparatus  10 ,  110  reports to the network node  120  if the FD mode is or is not possible because of reception gain loss and self-interference, for example, based on whether or not a reception quality parameter falls below a threshold, for example, a downlink sensitivity limit. 
     The real-time isolation value can, in at least some examples, be determined from a look-up table based on FD mode configuration and beam steering angle. 
     The use of real-time values enables dynamic adjustment to changes in the reception environment of the apparatus  10 ,  110 . The apparatus  10 ,  110  can therefore monitor the real-time value for gain loss at the apparatus  10 ,  110 , and, for example, send a report based on the measurement regularly to the network node  120 . 
     When the real-time value for gain loss at the apparatus  10 ,  110 , is good (not gain limited), the network node can command the apparatus  10 ,  110  to switch to (or to attempt to switch to) FD mode. The apparatus  10 ,  110  can then select an FD mode configuration. The FD mode configuration can for example depend upon the beam steering angle, transmit power, isolation, reception gain loss and reception sensitivity limit. 
     The FD mode configuration can be weighted towards gain (not isolation) when a lower uplink transmission power is used. For example, more antenna elements  12  can be used for reception and less or no antenna elements can be configured for non-use isolation. 
     The FD mode configuration can be weighted towards isolation (not gain) when a higher uplink transmission power is used. For example, less antenna elements  12  can be used for reception and some or more antenna elements  12  can be configured for non-use isolation. 
     Therefore, the apparatus  10 ,  110  can in some examples, flexibly switch into or out of the full duplex mode of operation. In some examples, the switch can be dependent upon a reception quality parameter measured at the apparatus. 
     As illustrated in  FIG.  11   , the serving network node  120  (gNB) can schedule the apparatus  10 ,  110  (UE) for split antenna panel FD mode only at steering angles providing for required isolation, when the uplink is not power limited and the downlink is not below the sensitivity limit. 
     Referring to  FIG.  11   , initially FD mode has been prevented or is by default not carried out following a command (SS-BLOCK)  201  sent from the network node  120  to the apparatus  10 ,  110 . 
     The apparatus  10 ,  110  sends an indication  203  of its FD capability to the network node  120  during cell camping. One option is to include the UE FD capability in the general UE capability reporting. UE capability Information is an RRC message that the UE sends to the Network in most cases during initial access/registration process (i.e. when it is camping onto the cell). It informs on all the details of the UE capabilities. In RRC connected the serving gNB sends a UE capability enquiry and the UE responds with the UE capability information report. 
     The apparatus  10 ,  110  is controlled  205  by the network node  120  to enter RRC connected state in TDD mode. The apparatus  10 ,  110  then uses  206  the array  14  of antenna elements in TDD mode ( FIG.  2 A ). 
     The network node  120  requests  207  the apparatus  10 ,  110  to evaluate whether FD mode is possible. Due to the split-antenna gain loss, the network node  120  will not request FD evaluation if it knows that the uplink is power limited. 
     The apparatus  10 ,  110  measures  208  a current reception quality parameter e.g. RSRP. 
     The apparatus  10 ,  110  can infer than the reception gain loss is insufficient for current beam steering angle (i.e. downlink power below sensitivity limit) when the current reception quality parameter e.g. RSRP falls below a defined lower limit. The sensitivity limit is defined as the lowest receive power level at which the downlink can still be decoded at a given bit error rate. 
     The apparatus  10 ,  110  evaluates  208  the isolation of one or more FD mode configurations based on a current beam steering angle. This can, for example, be a memory access by controller  50  to a stored look-up table. The apparatus  10 ,  110  determines a current isolation based on a pre-determined FD mode look-up table for the current beam steering angle and the current measured reception quality parameter e.g. RSRP. 
     The apparatus  10 ,  110  reports  211  to the network node if FD mode is not possible  210 , for example: 
     (i) if isolation is insufficient for current beam steering angle and uplink transmission power (i.e. uplink is power limited); and/or 
     (ii) if reception gain loss is insufficient for current beam steering angle (i.e. downlink power below sensitivity limit; reception quality parameter below a threshold) 
     The apparatus  10 ,  110  reports  213  to the network node if FD mode is possible  212 , for example: 
     (i) if isolation is sufficient for current beam steering angle and uplink transmission power (i.e. uplink is NOT power limited) 
     (ii) if reception gain loss is sufficient for current beam steering angle (i.e. downlink power above sensitivity limit) 
     The network node responds by scheduling  215  the apparatus  10 ,  110  in FD mode. The apparatus  10 ,  110 , in response to the network node  120 , enters FD mode  216  and splits the antenna array  14  according to an FD mode configuration that has sufficient isolation and sufficient reception gain. 
     The method can then be regularly repeated from the network node requests  207  that request the apparatus  10 ,  110  to evaluate whether FD mode is possible. 
     If the FD mode is no longer possible for the apparatus  10 ,  110  the network node  120  schedules  205 ,  206  TDD mode operation for the apparatus  10 ,  110 . This could, for example, be in response to receiving at the network node  110  a report  211  that the FD mode is not possible at the apparatus  10 ,  110 . It could also be in response to the network node  120  determining that the uplink is or is likely to be power limited. 
       FIG.  12    is similar to  FIG.  11    and similar references are used to reference similar steps, which for brevity will not be re-described here. The method of  FIGS.  11  and  12    are the same until after the apparatus  10 ,  110 , in response to the network node  120 , enters FD mode  216  and splits the antenna array  14  according to an FD mode configuration that has sufficient isolation and sufficient reception gain. 
       FIG.  12    illustrates that the FD mode configuration can be dynamic and can be changed to maintain sufficient isolation and sufficient reception gain. 
     The FD mode configuration can be weighted towards gain (not isolation) when a lower uplink transmission power is used. For example, more antenna elements can be used for reception and less or no antenna elements can be configured for non-use isolation. 
     The FD mode configuration can be weighted towards isolation (not gain) when a higher uplink transmission power is used. For example, less antenna elements  12  can be used for reception and some or more antenna elements  12  can be configured for non-use isolation. 
     The different FD mode configurations can be pre-determined and parameters for setting up the different FD mode configuration can be stored in a look-up table. The FD mode configurations can, for example, comprise different entries for different FD mode configurations and beam steering angles, with each entry specifying which antenna elements/RF paths are to be used for transmission and which for reception, and control parameters for phase shifters and amplifiers in the transmission radio frequency paths and the reception radio frequency paths. 
     In the field, the isolation may be impacted by the environment dynamics etc. and control parameters for phase shifters and amplifiers can be varied to maintain beam steering direction/gain and isolation. 
     At block  220 , the apparatus  10 ,  110  detects poor reception quality. The apparatus  10 ,  110  can communicate  221  with the network node  110  to assess reception gain loss. 
     The gain loss at the mobile equipment  10 ,  110  is determined by communication  221  between the network node  120  and the apparatus  10 ,  110 . The network node  120  transmits a reference signal of known power to the apparatus  10 ,  110 . The network node  120  measured the power of the reference signal on reception. The ratio provides the gain loss. 
     The isolation at the mobile equipment  10 ,  110  is determined by measuring RSRP. 
     If the isolation is inadequate, it can be improved by maintaining the same FD mode configuration (same split between reception RF paths  20   R , transmission RF paths  20   T  and optionally non-use isolating RF paths  20   I ) but changing the control parameters for phase shifters  70  and amplifiers  72  can be varied to maintain beam steering direction/gain and isolation. 
     Alternatively, If the isolation is inadequate, it can be improved by changing the FD mode configuration (different split between reception RF paths  20   R , transmission RF paths  20   T  and optionally non-use isolating RF paths  20   I ). 
     If the isolation cannot be made adequate, then an appropriate report  211  is sent to the network node  120 . 
     The communication  221  with the network node  120  to assess reception gain loss is optional. 
     In the figures the interconnection of elements means that they are operationally coupled and any number or combination of intervening elements can exist (including no intervening elements). 
     Where a structural feature has been described, it may be replaced by means for performing one or more of the functions of the structural feature whether that function or those functions are explicitly or implicitly described. 
     The data may be stored in processed or unprocessed format remotely at one or more devices. The data may be stored in the Cloud. 
     The data may be processed remotely at one or more devices. The data may be partially processed locally and partially processed remotely at one or more devices. 
     The data may be communicated to the remote devices wirelessly via short range radio communications such as Wi-Fi or Bluetooth, for example, or over long range cellular radio links. The apparatus may comprise a communications interface such as, for example, a radio transceiver for communication of data. 
     The apparatus  110  may be part of the Internet of Things forming part of a larger, distributed network. 
     The processing of the data, whether local or remote, may be for the purpose of health monitoring, data aggregation, patient monitoring, vital signs monitoring or other purposes. 
     The processing of the data, whether local or remote, may involve artificial intelligence or machine learning algorithms. The data may, for example, be used as learning input to train a machine learning network or may be used as a query input to a machine learning network, which provides a response. The machine learning network may for example use linear regression, logistic regression, vector support machines or an acyclic machine learning network such as a single or multi hidden layer neural network. 
     The processing of the data, whether local or remote, may produce an output. The output may be communicated to the apparatus  10  where it may produce an output sensible to the subject such as an audio output, visual output or haptic output. 
     The recording of data may comprise only temporary recording, or it may comprise permanent recording or it may comprise both temporary recording and permanent recording, Temporary recording implies the recording of data temporarily. This may, for example, occur during sensing or image capture, occur at a dynamic memory, occur at a buffer such as a circular buffer, a register, a cache or similar. Permanent recording implies that the data is in the form of an addressable data structure that is retrievable from an addressable memory space and can therefore be stored and retrieved until deleted or over-written, although long-term storage may or may not occur. The use of the term ‘store’ in relation to data relates to permanent recording of the data of the image. 
     An operational resonant mode (operational bandwidth) is a frequency range over which an antenna element  12  can efficiently operate. An operational resonant mode (operational bandwidth) may be defined as where the return loss S 11  of the antenna element  12  is greater than an operational threshold T such as, for example, −6 or −10 dB. The antenna elements  12  can be configured to operate with the same operational bandwidths. 
     As used here ‘module’ refers to a unit or apparatus that excludes certain parts/components that would be added by an end manufacturer or a user. The apparatus  10  can be a module. 
     The above described examples find application as enabling components of: automotive systems; telecommunication systems; electronic systems including consumer electronic products; distributed computing systems; media systems for generating or rendering media content including audio, visual and audio visual content and mixed, mediated, virtual and/or augmented reality; personal systems including personal health systems or personal fitness systems; navigation systems; user interfaces also known as human machine interfaces; networks including cellular, non-cellular, and optical networks; ad-hoc networks; the internet; the internet of things; virtualized networks; and related software and services. 
     The term ‘comprise’ is used in this document with an inclusive not an exclusive meaning. That is any reference to X comprising Y indicates that X may comprise only one Y or may comprise more than one Y. If it is intended to use ‘comprise’ with an exclusive meaning then it will be made clear in the context by referring to “comprising only one.” or by using “consisting”. 
     In this description, reference has been made to various examples. The description of features or functions in relation to an example indicates that those features or functions are present in that example. The use of the term ‘example’ or ‘for example’ or ‘can’ or ‘may’ in the text denotes, whether explicitly stated or not, that such features or functions are present in at least the described example, whether described as an example or not, and that they can be, but are not necessarily, present in some of or all other examples. Thus ‘example’, ‘for example’, ‘can’ or ‘may’ refers to a particular instance in a class of examples. A property of the instance can be a property of only that instance or a property of the class or a property of a sub-class of the class that includes some but not all of the instances in the class. It is therefore implicitly disclosed that a feature described with reference to one example but not with reference to another example, can where possible be used in that other example as part of a working combination but does not necessarily have to be used in that other example. 
     Although examples have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the claims. 
     Features described in the preceding description may be used in combinations other than the combinations explicitly described above. 
     Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not. 
     Although features have been described with reference to certain examples, those features may also be present in other examples whether described or not. 
     The term ‘a’ or ‘the’ is used in this document with an inclusive not an exclusive meaning. That is any reference to X comprising a/the Y indicates that X may comprise only one Y or may comprise more than one Y unless the context clearly indicates the contrary. If it is intended to use ‘a’ or ‘the’ with an exclusive meaning then it will be made clear in the context. In some circumstances the use of ‘at least one’ or ‘one or more’ may be used to emphasis an inclusive meaning but the absence of these terms should not be taken to infer any exclusive meaning. 
     The presence of a feature (or combination of features) in a claim is a reference to that feature or (combination of features) itself and also to features that achieve substantially the same technical effect (equivalent features). The equivalent features include, for example, features that are variants and achieve substantially the same result in substantially the same way. The equivalent features include, for example, features that perform substantially the same function, in substantially the same way to achieve substantially the same result. 
     In this description, reference has been made to various examples using adjectives or adjectival phrases to describe characteristics of the examples. Such a description of a characteristic in relation to an example indicates that the characteristic is present in some examples exactly as described and is present in other examples substantially as described. 
     Whilst endeavoring in the foregoing specification to draw attention to those features believed to be of importance it should be understood that the Applicant may seek protection via the claims in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not emphasis has been placed thereon.