Patent Publication Number: US-2023155290-A1

Title: Interleaved antenna array configuration in a radio node

Description:
TECHNICAL FIELD 
     The technology of the disclosure relates generally to configuring an antenna array having multiple antennas in a wireless communications network, such as a fifth generation new radio (5G-NR) cellular communications network. 
     BACKGROUND 
     Fifth generation new radio (5G-NR) is a new radio access technology (RAT) widely regarded as the next generation of RAT beyond the current third generation (3G) and fourth generation (4G) RATs. A 5G-NR radio node, such as an infrastructure base station (BS) or a user equipment (UE), can be configured to transmit a radio frequency (RF) signal(s) in a spectrum(s) that can be above or below 6 GHz. Given that some part of the spectrum(s) may be susceptible to interference and propagation loss, massive multiuser (MU) multiple-input multiple-output (MIMO) and spatial filtering (a.k.a., beamforming) are expected to be core technologies of the 5G-NR RAT for achieving high-bandwidth data transmission to multiple UEs. 
     In this regard, the 5G-NR radio node is commonly configured to utilize multiple antennas to radiate the RF signal(s) simultaneously. The multiple antennas are typically organized into an antenna array having multiple rows and columns (e.g., 4×4, 8×8, 16×16, etc.). The 5G-NR radio node may pre-code the RF signal(s) into multiple weighted RF signals, each having a respective weight corresponding to a respective one of the multiple antennas. In addition, the 5G-NR radio node typically employs a number of power amplifiers to amplify the weighted RF signals before feeding the amplified weighted RF signals to the multiple antennas via respective antenna paths. 
     The 5G-NR radio node may be required to simultaneously communicate with a large number of UEs via multiple RF channels in the mmWave spectrum(s). In addition, the 5G-NR radio node may need to co-exist and/or co-operate with conventional 3G and 4G radio nodes in a wireless communications cell. As such, the third-generation partnership project (3GPP) has established stringent RF performance requirements to help reduce interferences among RF channels and between different RATs. For example, 3GPP requires the 5G-NR radio node to limit adjacent channel leakage ratio (ACLR) to −45 dBc or below for mid-band transmitters operating in sub-6 GHz spectrum. 
     Notably, the power amplifiers can be inherently nonlinear. As a result, the amplified weighted RF signals may be distorted by the power amplifiers during amplification. In addition, the amplified weighted RF signals may be further distorted by the antenna paths connecting the power amplifiers to the antennas due to signal leakage (a.k.a. crosstalk) between the antenna paths. Thus, it may be desirable to reduce the nonlinearity distortion and the signal leakage in the 5G-NR radio node to satisfy the stringent 3GPP RF performance requirements. 
     SUMMARY 
     Embodiments disclosed herein include an interleaved antenna array configuration in a radio node. The antenna array includes a mixture of isolated and non-isolated antenna elements. The isolated antenna elements are each protected by a respective antenna isolator. In contrast, the non-isolated antenna elements are coupled to respective simplified digital pre-distortion (DPD) actuators (also referred to as “simplified DPD circuit” hereinafter) without respective antenna isolators. In examples discussed herein, the isolated and non-isolated antenna elements are interleaved in each row and each column of the antenna array. More specifically, each isolated antenna element is only adjacent to one or two non-isolated antenna elements in each row and each column. Likewise, each non-isolated antenna element is only adjacent to one or two isolated antenna elements in each row and each column. By interleaving the isolated and non-isolated antenna elements in each row and column of the antenna array, it is possible to reduce a number of antenna isolators, thus helping to reduce cost and footprint of the radio node. In addition, by using a combination of antenna isolators and simplified DPD circuits in association with the interleaved antenna array, the radio node is able to satisfy stringent radio frequency (RF) performance requirements, such as the RF performance requirements mandated by third-generation partnership project (3GPP) and/or regulatory authorities. 
     In one embodiment, a radio node is provided. The radio node includes an antenna array comprising a plurality of isolated antenna elements and a plurality of non-isolated antenna elements disposed in a first number of rows and a second number of columns. The plurality of isolated antenna elements and the plurality of non-isolated antenna elements are interleaved in each of the first number of rows and each of the second number of columns. The antenna array also includes a plurality antenna isolators each coupled to a respective one of the plurality of isolated antenna elements. The radio node also includes a plurality of non-isolated amplifier circuits each coupled to a respective one of the plurality of non-isolated antenna elements in the antenna array. 
     In another embodiment, a method for configuring an antenna array in a radio node is provided. The method includes disposing a plurality of isolated antenna elements and a plurality of non-isolated antenna elements in a first number of rows and a second number of columns of an antenna array such that the plurality of isolated antenna elements and the plurality of non-isolated antenna elements are interleaved in each of the first number of rows and each of the second number of columns. The method also includes coupling a plurality of antenna isolators to the plurality of isolated antenna elements in the antenna array, respectively. The method also includes coupling each of a plurality of non-isolated amplifier circuits to a respective one of the plurality of non-isolated antenna elements in the antenna array. 
     In another embodiment, a method for operating a radio node is provided. The radio node comprises an antenna array that comprises a plurality of isolated antenna elements and a plurality of non-isolated antenna elements that are interleaved in each row and each column. The method includes performing a first type of DPD to pre-distort a first digital signal. The method also includes converting the pre-distorted first digital signal into a first RF signal. The method also includes amplifying the first RF signal to generate a first amplified RF signal. The method also includes providing the first amplified RF signal to a respective one of the plurality of isolated antenna elements. The method also includes performing a second type of DPD to pre-distort a second digital signal. The method also includes converting the pre-distorted second digital signal into a second RF signal. The method also includes amplifying the second RF signal to generate a second amplified RF signal. The method also includes providing the second amplified RF signal to a respective one of the plurality of non-isolated antenna elements. 
     In another embodiment, a radio node is provided. The radio node includes an antenna array includes a plurality of isolated sub-arrays and a plurality of non-isolated sub-arrays. The plurality of isolated sub-arrays and the plurality of non-isolated antenna sub-arrays are interleaved. The radio node also includes a plurality of antenna isolators each coupled to a respective one of the plurality of isolated sub-arrays. The radio node also includes a plurality of isolated amplifier circuits each coupled to a respective antenna isolator among the plurality of antenna isolators. The radio node also includes a plurality of non-isolated amplifier circuits each coupled to a respective one of the plurality of non-isolated sub-arrays in the antenna array. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure. 
         FIG.  1 A  is a schematic diagram of an exemplary existing isolator-protected antenna array in which each antenna element is coupled to and protected by a dedicated antenna isolator; 
         FIG.  1 B  is a schematic diagram of an exemplary existing isolator-free antenna array in which each antenna element is not coupled to and protected by a dedicated antenna isolator; 
         FIG.  1 C  is a schematic diagram providing an exemplary illustration of a dual-input power amplifier (DI-PA) model as described in U.S. Patent Application Publication Number 2018/0167092 A1 to Hausmair et al.; 
         FIG.  1 D  is a schematic diagram providing an exemplary digital pre-distortion (DPD) block diagram for implementing DI-PA DPD based on the DI-PA model in  FIG.  1 C ; 
         FIG.  2 A  is a schematic diagram of an exemplary radio node including an antenna array configured according to an interleaved configuration of the present disclosure; 
         FIG.  2 B  is a schematic diagram of an exemplary radio node including an antenna array configured according to another interleaved configuration of the present disclosure; 
         FIGS.  3 A- 3 C  are schematic diagrams providing exemplary illustrations of a non-isolated antenna element that may be surrounded by up to four isolated antenna elements in the antenna array of  FIG.  2 A ; 
         FIGS.  4 A- 4 B  are flowcharts illustrating an exemplary method for configuring the antenna array in the radio node of  FIG.  2 A ; 
         FIG.  4 C  is a flowchart illustrating an exemplary method for operating the radio node of  FIG.  2 A ; 
         FIG.  5    is a schematic diagram of an exemplary antenna array having a different polarization from the antenna array in  FIG.  2 A  and configured according to the interleaved configuration of the present disclosure; 
         FIG.  6 A  is a schematic diagram of an exemplary radio node including a dual-polarization antenna array that is formed by stacking the antenna array in  FIG.  2 A  and the antenna array in  FIG.  5   ; 
         FIG.  6 B  is an exemplary cross-section view of the dual-polarization antenna array of  FIG.  6 A ; 
         FIG.  6 C  is a schematic diagram of an exemplary radio node including a dual-polarization antenna array that is formed by stacking two antenna arrays according to an alternative configuration; 
         FIG.  6 D  is an exemplary cross-section view of the dual-polarization antenna array in  FIG.  6 C ; 
         FIG.  7    illustrates one example of a cellular communications network in which embodiments of the present disclosure may be implemented to provide the radio nodes in  FIGS.  2 A,  2 B, and  6 A ; 
         FIG.  8    is a schematic block diagram of a radio access node according to some embodiments of the present disclosure; 
         FIG.  9    is a schematic block diagram of the radio access node of  FIG.  8    according to some other embodiments of the present disclosure; 
         FIG.  10    is a schematic block diagram that illustrates a virtualized embodiment of the radio access node of  FIG.  8    according to some embodiments of the present disclosure; 
         FIG.  11    is a schematic block diagram of a UE according to some embodiments of the present disclosure; and 
         FIG.  12    is a schematic block diagram of the UE of  FIG.  11    according to some other embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure. 
     Radio Node: As used herein, a “radio node” is either a radio access node or a wireless communication device. 
     Radio Access Node: As used herein, a “radio access node” or “radio network node” or “radio access network node” is any node in a Radio Access Network (RAN) of a cellular communications network that operates to wirelessly transmit and/or receive signals. Some examples of a radio access node include, but are not limited to, a base station (e.g., a New Radio (NR) base station (gNB) in a Third Generation Partnership Project (3GPP) Fifth Generation (5G) NR network or an enhanced or evolved Node B (eNB) in a 3GPP Long Term Evolution (LTE) network), a high-power or macro base station, a low-power base station (e.g., a micro base station, a pico base station, a home eNB, or the like), a relay node, a network node that implements part of the functionality of a base station or a network node that implements a gNB Distributed Unit (gNB-DU)) or a network node that implements part of the functionality of some other type of radio access node. 
     Core Network Node: As used herein, a “core network node” is any type of node in a core network or any node that implements a core network function. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), a Home Subscriber Server (HSS), or the like. Some other examples of a core network node include a node implementing an Access and Mobility Function (AMF), a User Plane Function (UPF), a Session Management Function (SMF), an Authentication Server Function (AUSF), a Network Slice Selection Function (NSSF), a Network Exposure Function (NEF), a Network Function (NF) Repository Function (NRF), a Policy Control Function (PCF), a Unified Data Management (UDM), or the like. 
     Communication Device: As used herein, a “communication device” is any type of device that has access to an access network. Some examples of a communication device include, but are not limited to: mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or Personal Computer (PC). The communication device may be a portable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice and/or data via a wireless or wireline connection. 
     Wireless Communication Device: One type of communication device is a wireless communication device, which may be any type of wireless device that has access to (i.e., is served by) a wireless network (e.g., a cellular network). Some examples of a wireless communication device include, but are not limited to: a User Equipment device (UE) in a 3GPP network, a Machine Type Communication (MTC) device, and an Internet of Things (IoT) device. Such wireless communication devices may be, or may be integrated into, a mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or PC. The wireless communication device may be a portable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice and/or data via a wireless connection. 
     Network Node: As used herein, a “network node” is any node that is either part of the RAN or the core network of a cellular communications network/system. 
     Note that the description given herein focuses on a 3GPP cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system. 
     Note that, in the description herein, reference may be made to the term “cell”; however, particularly with respect to 5G NR concepts, beams may be used instead of cells and, as such, it is important to note that the concepts described herein are equally applicable to both cells and beams. 
     Embodiments disclosed herein include an interleaved antenna array configuration in a radio node. The antenna array includes a mixture of isolated and non-isolated antenna elements. The isolated antenna elements are each protected by a respective antenna isolator. In contrast, the non-isolated antenna elements are coupled to respective simplified digital pre-distortion (DPD) circuits without respective antenna isolators. In examples discussed herein, the isolated and non-isolated antenna elements are interleaved in each row and each column of the antenna array. More specifically, each isolated antenna element is only adjacent to one or two non-isolated antenna elements in each row and each column. Likewise, each non-isolated antenna element is only adjacent to one or two isolated antenna elements in each row and each column. By interleaving the isolated and non-isolated antenna elements in each row and column of the antenna array, it is possible to reduce the number of antenna isolators, thus helping to reduce cost and footprint of the radio node. In addition, by using a combination of antenna isolators and simplified DPD circuits in association with the interleaved antenna array, the radio node is able to satisfy stringent radio frequency (RF) performance requirements, such as the RF performance requirements mandated by 3GPP and/or regulatory authorities. 
     For the convenience of illustration and reference, a three-by-three (3×3) antenna array, which includes nine (9) antenna elements disposed in 3 rows and 3 columns, is used hereinafter as a non-limiting example. It should be appreciated that any configuration discussed hereinafter with reference to the 3×3 antenna array is generally applicable to any antenna array of any dimension. 
     Before discussing the interleaved antenna array configuration of the present disclosure, starting at  FIG.  2 A , a brief overview of some existing antenna array configurations is first provided with reference to  FIGS.  1 A- 1 D . 
       FIG.  1 A  is a schematic diagram of an exemplary existing isolator-protected antenna array  100  in which each antenna element  102  is coupled to and protected by a dedicated antenna isolator  104 . In the isolator-protected antenna array  100 , each antenna element  102  is coupled to a respective power amplifier  106 , a respective digital-to-analog converter (DAC)  108 , and a respective conventional DPD circuit  110  (denoted as Single-Input-Single-Output DPD or “SISO DPD”). Notably, only two power amplifiers  106 , two DACs  108 , and two conventional DPD circuits  110  are shown therein in  FIG.  1 A  for the sake of brevity. 
     The DAC  108  is adapted to convert a digital signal  112  into an RF signal  114 . The power amplifier  106  amplifies the RF signal  114  to generate an amplified RF signal  116 . The amplified RF signal  116  is provided to a respective antenna element  102  via a respective antenna path  118 . 
     As previously mentioned, the power amplifier  106  can be inherently nonlinear. As a result, the amplified RF signal  116  may be distorted by the power amplifier  106  during amplification. In addition, the amplified RF signal  116  may be further distorted along the antenna path  118  connecting the power amplifier  106  to the antenna element  102  due to signal leakage (a.k.a. crosstalk). As such, the isolator  104  is provided in the antenna path  118  in between the respective power amplifier  106  and the respective antenna element  102  to help reduce the distortion resulting from signal leakage (a.k.a. crosstalk). In addition, the conventional DPD circuit  110  can be configured to digitally pre-distort the digital signal  112  to help compensate for the nonlinearity distortion produced by the power amplifier  106 . By employing the antenna isolator  104  and the conventional DPD circuit  110  to reduce crosstalk and nonlinearity distortion for each antenna element  102 , the existing isolator-protected antenna array  100  may be able to satisfy the stringent RF performance requirements, such as adjacent channel leakage ratio (ACLR), mandated by the 3GPP and/or regulatory authorities. 
     However, given that the isolator-protected antenna array  100  may be scaled to include tens or even hundreds of the antenna elements  102 , using a dedicated antenna isolator to protect each of the antenna elements  102  can cause significant cost and size increase of the isolator-protected antenna array  100 . In addition, employing an excessive number of the antenna isolators  104  can also introduce significant insertion losses, which may cause a power loss in the amplified RF signals  116 . Moreover, in a bandlimited device (e.g., the antenna isolators  104 ), the antenna isolators  104  may also distort wideband signals. Thus, it may be necessary to increase a power level of the RF signals  114  to help compensate for the power reduction caused by the insertion losses. As a result, the power amplifiers  106  can cause increased power consumption and heat dissipation in the existing isolator-protected antenna array  100 . 
     To help mitigate the cost and size impact associated with the antenna isolators  104 ,  FIG.  1 B  is a schematic diagram of an exemplary existing isolator-free antenna array  120  in which each antenna element  102  is not coupled to and protected by a dedicated antenna isolator. Common elements between  FIGS.  1 A and  1 B  are shown therein with common element numbers and will not be re-described herein. 
     As illustrated in  FIG.  1 B , in each antenna path  118 , the power amplifier  106  is coupled to a respective one of the antenna elements  102  without employing the antenna isolator  104  in  FIG.  1 A . Instead, each antenna element  102  is coupled to a dual-input power amplifier (DI-PA) DPD circuit  122  that aims to reduce both the nonlinearity distortion caused by the power amplifier  106  and the crosstalk distortion association with the antenna path  118 . The DI-PA DPD circuit  122  is configured to operate based on a DI-PA model that has been described in detail in U.S. Patent Application Publication Number 2018/0167092 A1 to Hausmair et al. (hereinafter “Hausmair”). 
     In this regard,  FIG.  1 C  is a schematic diagram providing an exemplary illustration of a DI-PA model  124  as described in Hausmair. Notably in  FIG.  1 C , the antenna element  102  in  FIG.  1 B  is represented by antenna elements  102 ( 1 )- 102 (K), the power amplifier  106  in  FIG.  1 B  is represented by power amplifiers  106 ( 1 )- 106 (K), and the antenna path  118  in  FIG.  1 B  is represented by antenna paths  118 ( 1 )- 118 (K). In this regard, the antenna elements  102 ( 1 )- 102 (K) are coupled to the power amplifiers  106 ( 1 )- 106 (K) by the antenna paths  118 ( 1 )- 118 (K), respectively. 
     According to Hausmair, the DI-PA model  124  model includes two main blocks, namely a crosstalk and mismatch model (CTM) and a nonlinear dual-input DPD model. The CTM models the crosstalk and mismatch among the antenna paths  118 ( 1 )- 118 (K). In contrast, there is a respective nonlinear dual-input DPD model for each of the antenna paths  118 ( 1 )- 118 (K). Specifically, each of the power amplifiers  106 ( 1 )- 116 (K) may be modeled to have a direct DI-PA input a 1i (n), a second DI-PA input a 2i (n) (also referred to as an “indirect DI-PA input” hereinafter for the purpose of distinction), and a PA output b 2i (n) (1≤i≤K). The CTM is a function of the PA output b 2i (n), which can be expressed as in equation (Eq. 1) below. 
     
       
         
           
             
               
                 
                   
                     
                       
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     In the equation (Eq. 1) above, P 1  . . . P 4 , m 1  . . . m 8  represent different nonlinearity orders and memory depths for different terms, α, β, γ, and δ are model coefficients corresponding to subscripted bases and indices. The PA output b 2i (n) can also be expressed in a matrix form, as shown below in equation (Eq. 2). 
         b   2   =H ( a   1   ,a   2 )θ  (Eq. 2)
 
     In the equation (Eq. 2) above, b 2  is an output vector of a sufficiently large sample size, a 1  and a z  are corresponding DI-PA model input vectors, H is a regression matrix accommodating different bases, and θ is the model parameters vector composed of concatenated α, β, γ, and δ vectors. In a non-limiting example, θ can be determined based on a least square solution, as expressed below in equation (Eq. 3). 
       θ=( H   H   H ) −1   H   H   b   2   (Eq. 3)
 
     Notably, if each of the antenna paths  118 ( 1 )- 118 (K) is protected by a respective antenna isolator  104  in  FIG.  1 A , then the second DI-PA input a 2i (n) will become zero (0). Accordingly, the PA output b 2i (n) can be expressed by equation (Eq. 4) below. 
     
       
         
           
             
               
                 
                   
                     
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     The DI-PA DPD may be implemented based on a direct learning architecture, in which a post distorter is used as an estimate of a pre-distorter, for a linear gain G. In this regard,  FIG.  1 D  is a schematic diagram providing an exemplary DPD block diagram  126  for implementing DI-PA DPD based on the DI-PA model in  FIG.  1 C . Herein, the DPD coefficients can be estimated based on equation (Eq. 5) below. 
     
       
         
           
             
               
                 
                   
                     
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     Again with a pre  being the pre-distorted signal using the DPD coefficients estimated at previous iteration, if each of the antenna paths  118 ( 1 )- 118 (K) is protected by a respective antenna isolator  104  in  FIG.  1 A , then the DPD coefficients may be estimated based on equation (Eq. 6) below. 
     
       
         
           
             
               
                 
                   
                     
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     Notably, in the equation (Eq. 5), a 2  is not a dependent variable from b 2 . In this regard, Hausmair proposes to estimate the CTM via an iterative process. Please refer to Hausmair for further details related to CTM estimation. It should be noted that mutual leakage among the antenna paths  118 ( 1 )- 118 (K) may lead to an increase in nonlinearity distortion. As a result, the existing isolator-free antenna array  120  may not be able to satisfy the stringent RF performance requirements mandated by the 3GPP. As discussed above, the existing isolator-protected antenna array  100  in  FIG.  1 A  may satisfy the stringent RF performance requirements at an expense of increased size and cost. In contrast, the existing isolator-free antenna array  120  in  FIG.  1 B  may be implemented with a smaller size and cost compared to the existing isolator-protected antenna array  100  but may not be able to satisfy the stringent RF performance requirements mandated by the 3GPP. In this regard, it may be desirable to implement an antenna array with lower size and cost to satisfy the stringent RF performance requirements mandated by the 3GPP. 
     In this regard,  FIG.  2 A  is a schematic diagram of an exemplary radio node  200  including an antenna array  202  configured according to an interleaved configuration of the present disclosure. As discussed in detail below, the antenna array  202  includes a mixture of isolated and non-isolated antenna elements. For the sake of distinction, an antenna element that is coupled to and protected by a dedicated antenna isolator in a respective antenna path (e.g., as in the existing isolator-protected antenna array  100  of  FIG.  1 A ) is hereinafter referred to as an “isolated antenna element.” In contrast, an antenna element that is not coupled to and not protected by a dedicated antenna isolator in a respective antenna path (e.g., as in the existing isolator-free antenna array  120  of  FIG.  1 B ) is hereinafter referred to as a “non-isolated antenna element.” By interleaving the isolated and non-isolated antenna elements in each row and each column of the antenna array  200 , it is possible to reduce the number of antenna isolators, thus helping to reduce cost and footprint of the antenna array  200 . In addition, by using a combination of antenna isolators and DI-PA DPD for some antenna elements in the antenna array  200  in an interleaved manner, it is possible to satisfy stringent radio RF performance requirements, such as the RF performance requirements mandated by the 3GPP. Further, by interleaving the isolated and non-isolated antenna elements, it may also be possible to reduce insertion losses caused by the antenna isolators, thus helping to reduce power consumption and heat dissipation in the radio node  200 . Furthermore, it may also help to improve receive sensitivity of the antenna array  202  in a time-division duplexing (TDD) system, as an example. 
     In a non-limiting example, the antenna array  202  includes antenna elements  204 ( 1 )- 204 ( 9 ) that are disposed in a first number (M) of rows and a second number (N) of columns. In the specific example shown in  FIG.  2 A , the antenna elements  204 ( 1 )- 204 ( 9 ) are disposed in three (3) rows (M=3) and 3 columns (N=3). It should be appreciated that the antenna array  200  can include additional antenna elements and M can be equal to or different from N. 
     Among the antenna elements  204 ( 1 )- 204 ( 9 ), the antenna elements  204 ( 2 ),  204 ( 4 ),  204 ( 6 ), and  204 ( 8 ) are isolated antenna elements, while the antenna elements  204 ( 1 ),  204 ( 3 ),  204 ( 5 ),  204 ( 7 ), and  204 ( 9 ) are non-isolated antenna elements. The isolated antenna elements are interleaved with the non-isolated antenna element in each of the first number of rows and each of the second number of columns. 
     For example, in row  1 , the non-isolated antenna element  204 ( 1 ) is adjacent to the isolated antenna element  204 ( 2 ) only. In contrast, in row  2 , the non-isolated antenna element  204 ( 5 ) is adjacent to the isolated antenna elements  204 ( 4 ) and  204 ( 6 ). Likewise, in column  1 , the non-isolated antenna element  204 ( 1 ) is adjacent to the isolated antenna element  204 ( 4 ) only. In contrast, in column  2 , the non-isolated antenna element  204 ( 5 ) is adjacent to the isolated antenna elements  204 ( 2 ) and  204 ( 8 ). In this regard, each non-isolated antenna element is said to be adjacent to a respective one or two of the isolated antenna elements in each of the first number of rows and each of the second number of columns. Likewise, each isolated antenna element is said to be adjacent to a respective one or two of the non-isolated antenna elements in each of the first number of rows and each of the second number of columns. 
     Each of the isolated antenna elements in the antenna array  202  is coupled to a respective isolated amplifier circuit  206 . Similarly, each of the non-isolated antenna elements in the antenna array  202  is coupled to a respective non-isolated amplifier circuit  208 . Although  FIG.  2 A  only illustrates one isolated amplifier circuit  206  and one non-isolated amplifier circuit  208 , it should be understandable that the radio node  200  includes an equal number of isolated amplifier circuits as the isolated antenna elements, and an equal number of non-isolated amplifier circuits as the non-isolated antenna elements. It should be further noted that the phrases “isolated antenna element,” “non-isolated antenna element,” “isolated amplifier circuit,” and “non-isolated antenna circuit” are arbitrary terms for the purpose of distinction. These terms do not suggest how isolation is achieved in the radio node  200 . In fact, isolation is an attribute of either a power amplifier or a whole TX-branch, which protects the power amplifier by isolating the power amplifier from reflected back waves by employing an isolator between the power amplifier and respective antenna element. 
     In a non-limiting example, the isolated amplifier circuit  206  includes an antenna isolator  210  coupled to a respective one of the isolated antenna elements  204 ( 2 ),  204 ( 4 ),  204 ( 6 ), and  204 ( 8 ) in the antenna array  202 . The antenna isolator  210  is configured to isolate the respective isolated antenna element from mutual coupling (e.g., crosstalk) in the antenna array  202 . Although the antenna isolator  210  is shown as being outside the isolated amplifier circuit  206 , it should be appreciated that the antenna isolator  210  can be integrated with the isolated amplifier circuit  206 . 
     The isolated amplifier circuit  206  includes an isolated power amplifier  212  coupled to the antenna isolator  210 . The isolated power amplifier  212  is configured to amplify a respective RF signal  214  (also referred to as “first RF signal” hereinafter”) to generate a respective amplified RF signal  216  (also referred to as “first amplified RF signal” hereinafter). The isolated amplifier circuit  206  also includes a DAC  218  coupled to the isolated power amplifier  212 . The DAC  218  is configured to convert a respective digital signal  220  (also referred to as “first digital signal” hereinafter) into the RF signal  214 . The isolated amplifier circuit  206  also includes a DPD circuit  222  (denoted as “SISO DPD”) coupled to the DAC  218 . The DPD circuit  222  is configured to digitally pre-distort the digital signal  220  to reduce nonlinearity distortion caused by the isolated power amplifier  212  in the amplified RF signal  216 . 
     In another non-limiting example, the non-isolated amplifier circuit  208  includes a non-isolated power amplifier  224  coupled to a respective one of the non-isolated antenna elements in the antenna array  202 . The non-isolated power amplifier  224  is configured to amplify a respective RF signal  226  (also referred to as “second RF signal” hereinafter) to generate a respective amplified RF signal  228  (also referred to as “second amplified RF signal” hereinafter). The non-isolated amplifier circuit  208  also includes a DAC  230  coupled to the non-isolated power amplifier  224 . The DAC  230  is configured to convert a respective digital signal  232  (also referred to as “second digital signal” hereinafter) into the respective RF signal  226 . The non-isolated amplifier circuit  208  also includes a simplified DPD actuator  234  (denoted as “DI-PA DPD”) coupled to the DAC  230 . The simplified DPD circuit  234  is configured to pre-distort the digital signal  232  based on a simplified DI-PA DPD algorithm to reduce nonlinearity distortion caused by the non-isolated power amplifier  224  in the amplified RF signal  228 . In a non-limiting example, the simplified DPD actuator  234  is a physical circuit, such as a field-programmable gate array (FPGA) that implements the simplified DI-PA DPD algorithm. In this regard, the simplified DPD actuator  234  is referred interchangeably as “simplified DPD circuit” hereinafter. 
     The simplified DI-PA DPD algorithm disclosed herein may be seen as a simplification of the DI-PA DPD model described in Hausmair. Specifically, the simplified DI-PA DPD algorithm capitalizes on the fact that, as a result of interleaving the isolated antenna elements and the non-isolated antenna elements in the antenna array  200 , each non-isolated antenna element is adjacent to up to four (4) isolated antenna elements in the antenna array  202 . 
       FIGS.  3 A- 3 C  are schematic diagrams providing exemplary illustrations of a non-isolated antenna element  300  that may be surrounded by up to 4 isolated antenna elements  302  in the antenna array  202  of  FIG.  2 A . Herein, the non-isolated antenna element  300  can be any one of the non-isolated antenna elements  204 ( 1 ),  204 ( 3 ),  204 ( 5 ),  204 ( 7 ), and  204 ( 9 ) and the isolated antenna element  302  can be any one of the isolated antenna elements  204 ( 2 ),  204 ( 4 ),  204 ( 6 ), and  204 ( 8 ) in  FIG.  2 A .  FIG.  3 A  illustrates a scenario wherein the non-isolated antenna element  300  is surrounded by two isolated antenna elements  302 . For example, the non-isolated antenna element  300  can be the non-isolated antenna element  204 ( 1 ) in  FIG.  2 A , surrounded by the isolated antenna elements  204 ( 2 ) and  204 ( 4 ). In this regard, the two isolated antenna elements  302  are said to be immediately surrounding the non-isolated antenna  300 . 
       FIG.  3 B  illustrates a scenario wherein the non-isolated antenna element  300  is surrounded by three isolated antenna elements  302 . For example, the non-isolated antenna element  300  can be disposed on a first column in the antenna array  204  of  FIG.  2 A  (not shown). In this regard, the three isolated antenna elements  302  are said to be immediately surrounding the non-isolated antenna element  300 . 
       FIG.  3 C  illustrates a scenario wherein the non-isolated antenna element  300  is surrounded by four isolated antenna elements  302 . For example, the non-isolated antenna element  300  can be the non-isolated antenna element  204 ( 5 ) in  FIG.  2 A , surrounded by the isolated antenna elements  204 ( 2 ),  204 ( 4 ),  204 ( 6 ), and  204 ( 8 ). In this regard, the four isolated antenna elements  302  are said to be immediately surrounding the non-isolated antenna element  300 . 
     The non-isolated antenna element  300  is also surrounded by some other non-isolated antenna elements  304 . For example, the non-isolated antenna element  204 ( 5 ) in  FIG.  2 A  is surrounded by the non-isolated antenna elements  204 ( 1 ),  204 ( 3 ),  204 ( 7 ), and  204 ( 9 ). Unlike the immediately surrounding isolated antenna elements  302 , the non-isolated antenna elements  304  are said to diagonally surround the non-isolated antenna element  300 . Notably, the energy in a near field of the non-isolated antenna element  300  is proportional to 1/r 2 , wherein r represents a physical distance from an antenna element. As such, each of the non-isolated antenna elements  304  has a respective coupling distance r 1  to the non-isolated antenna element  300  that is 2 0.5  longer than a respective coupling distance r 2  between each of the isolated antenna elements  302  and the non-isolated antenna element  300 . As a result, the effective coupling between the non-isolated antenna element  300  and each of the isolated antenna elements  302  is approximately 3 dB lower that the effective coupling between the non-isolated antenna element  300  and each of the non-isolated antenna elements  304 . 
     With reference back to  FIG.  2 A , given that each of the non-isolated antenna elements in the antenna array  202  is only surrounded by up to four isolated antenna elements, the indirect DI-PA input a 2i (n) in the DI-PA DPD model (as shown in  FIG.  1 D ) becomes a function of up to four isolated antenna elements immediately surrounding a respective one of the non-isolated antenna elements coupled to the non-isolated power amplifier  224 . For example, in  FIG.  3 A , the indirect DI-PA input a 2i (n) for a respective non-isolated power amplifier  224  coupled to the non-isolated antenna element  300  is a function of the two isolated antenna elements  300  immediately surrounding the non-isolated antenna element  300 . Similarly, in  FIG.  3 B , the indirect DI-PA input a 2i (n) for a respective non-isolated power amplifier  224  coupled to the non-isolated antenna element  300  is a function of the three isolated antenna elements  300  immediately surrounding the non-isolated antenna element  300 . Likewise, in  FIG.  3 C , the indirect DI-PA input a 2i (n) for a respective non-isolated power amplifier  224  coupled to the non-isolated antenna element  300  is a function of the four isolated antenna elements  302  immediately surrounding the non-isolated antenna element  300 . Accordingly, the indirect DI-PA input a 2i (n) may be generalized as in equation (Eq. 7) below. 
         a   2i =Σ k∈x λ ik   b   2k   (Eq. 7)
 
     In the equation (Eq. 7) above, λ ik  represents a respective coupling between an i th  (e.g., the respective antenna path coupled to the non-isolated antenna element  300 ) and a k th  antenna path (e.g., a respective antenna path coupled to any one of the isolated antenna elements  302 ), b 2k  represents an output of the k th  antenna path, and the set x includes the up to four isolated antenna elements  302  immediately surrounding the non-isolated antenna element  300 , as illustrated in  FIGS.  3 A- 3 C . As previously mentioned in  FIG.  3 C , the effective coupling between the non-isolated antenna element  300  and each of the isolated antenna elements  302  is approximately 3 dB lower that the effective coupling between the non-isolated antenna element  300  and each of the non-isolated antenna elements  304 . As such, it may be possible to ignore the couplings between the non-isolated antenna element  300  and the non-isolated antenna elements  304 . As a result, b 2k  becomes independent from the indirect DI-PA input a 2i (n). Hence, the indirect DI-PA input a 2i (n) can be determined in a single step process. 
       FIG.  2 B  is a schematic diagram of an exemplary radio node  236  including an antenna array  238  configured according to another interleaved configuration of the present disclosure. Common elements between  FIGS.  2 A and  2 B  are shown therein with common element numbers and will not be re-described herein. 
     The antenna array  238  includes a plurality of isolated sub-arrays  240 ( 1 ),  240 ( 3 ) and a plurality of non-isolated sub-arrays  240 ( 2 ). Although the antenna array  238  is shown to only include two isolated sub-arrays  240 ( 1 ),  240 ( 3 ) and one non-isolated sub-array  240 ( 2 ), it should be appreciated that the antenna array  238  can include additional number of isolated sub-arrays and/or non-isolated sub-arrays. 
     Each of the isolated sub-arrays  240 ( 1 ),  240 ( 3 ) can include a plurality of isolated antenna elements, such as any of the isolated antenna elements  204 ( 2 ),  204 ( 4 ),  204 ( 6 ),  204 ( 8 ) in  FIG.  2 A . Similarly, each of the non-isolated sub-arrays  240 ( 2 ) can include a plurality of isolated antenna elements, such as any of the non-isolated antenna elements  204 ( 1 ),  204 ( 3 ),  204 ( 5 ),  204 ( 7 ),  204 ( 9 ) in  FIG.  2 A . 
     The radio node  236  can include a plurality of RF splitter/combiners  242  each coupled to a respective one of the isolated sub-arrays  240 ( 1 ),  240 ( 3 ) and the non-isolated sub-arrays  240 ( 2 ). In a non-limiting example, each of the RF splitter/combiners  242  splits a respective amplified RF signal among the first amplified RF signal  216  and the second amplified RF signal  228 . For example, the RF splitter/combiners  242  coupled to the isolated sub-array  240 ( 1 ) splits the first amplified RF signal  216  into a plurality of first split RF signals  244  and provides the first split RF signals  244  to each isolated antenna element in the isolated sub-array  240 ( 1 ). Similarly, the RF splitter/combiners  242  coupled to the non-isolated sub-array  240 ( 2 ) splits the second amplified RF signal  228  into a plurality of second split RF signals  246  and provides the second split RF signals  246  to each non-isolated antenna element in the non-isolated sub-array  240 ( 2 ). 
     As shown in  FIG.  2 B , each of the antenna isolators  210  is coupled to a respective one of the isolated sub-arrays  240 ( 1 ),  240 ( 3 ) via a respective one of the RF splitter/combiners  242  and each of the isolated amplifier circuits  206  is coupled to a respective one of the antenna isolators  210 . In contrast, each of the non-isolated amplifier circuits  208  is coupled to a respective one of the RF splitter/combiners  242  without employing the antenna isolator  210 . 
       FIGS.  4 A and  4 B  are flowcharts illustrating an exemplary method for configuring the antenna array  202  in the radio node  200  of  FIG.  2 A . The method includes disposing a plurality of isolated antenna elements  204 ( 2 ),  204 ( 4 ),  204 ( 6 ), and  204 ( 8 ) and a plurality of non-isolated antenna elements  204 ( 1 ),  204 ( 3 ),  204 ( 5 ),  204 ( 7 ), and  204 ( 9 ) in a first number (M) of rows and a second number (N) of columns in the antenna array  202  such that the isolated antenna elements  204 ( 2 ),  204 ( 4 ),  204 ( 6 ), and  204 ( 8 ) and the non-isolated antenna elements  204 ( 1 ),  204 ( 3 ),  204 ( 5 ),  204 ( 7 ), and  204 ( 9 ) are interleaved in each of the first number (M) of rows and each of the second number (N) of columns (step  400 ). More specifically, as illustrated in  FIG.  4 B , as a result of interleaving the isolated antenna elements with the non-isolated antenna elements, each of the isolated antenna elements is disposed adjacent to a respective one or two of the non-isolated antenna elements in each of the first number (M) of rows and each of the second number (N) of columns (step  400   a ). Further according to  FIG.  4 B , each of the non-isolated antenna elements is disposed adjacent to a respective one or two of the isolated antenna elements in each of the first number (M) of rows and each of the second number (N) of columns (step  400   b ). 
     The method also includes coupling a plurality of antenna isolators to the plurality of isolated antenna elements in the antenna array (step  402 ). 
     The method also includes coupling each of the plurality of non-isolated amplifier circuits  208  to a respective one of the non-isolated antenna elements in the antenna array  202  (step  404 ). 
       FIG.  4 C  is a flowchart illustrating an exemplary method for operating the radio node  200  of  FIG.  2 A . The method includes performing a first type of DPD to pre-distort the first digital signal  220  (step  406 ). In a non-limiting example, the first type of DPD can be a single-input single-output (SISO) DPD, such as the conventional DPD performed by the conventional DPD circuit  110  in  FIG.  1 A . The method also includes converting the pre-distorted first digital signal  220  into the first RF signal  214  (step  408 ). The method also includes amplifying the first RF signal  214  to generate the first amplified RF signal  216  (step  410 ). The method also includes providing the first amplified RF signal  216  to a respective one of the plurality of isolated antenna elements  204 ( 2 ),  204 ( 4 ),  204 ( 6 ),  204 ( 8 ) in the antenna array  202  (step  412 ). 
     The method includes performing a second type of DPD to pre-distort the second digital signal  232  (step  414 ). In a non-limiting example, the second type of DPD can be the simplified DI-PA DPD as described in  FIG.  2 A . The method also includes converting the pre-distorted second digital signal  232  into the second RF signal  226  (step  416 ). The method also includes amplifying the second RF signal  226  to generate the second amplified RF signal  228  (step  418 ). The method also includes providing the second amplified RF signal  228  to a respective one of the plurality of non-isolated antenna elements  204 ( 1 ),  204 ( 3 ),  204 ( 5 ),  204 ( 7 ),  204 ( 9 ) in the antenna array  202  (step  420 ). The interleaved antenna configuration as described above can bring noticeable benefits over the existing isolator-protected antenna array configuration of  FIG.  1 A  and the existing isolator-free antenna array configuration of  FIG.  1 B . In this regard, Table 1 below presents a summary of simulation findings. 
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 ACLR [dBc] 
                   
                 Effective 
                 # Isolator 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Antenna array #1 
                 Antenna array #2 
                 Antenna array #3 
                 #DPD coef. 
                 # DPD coef. 
                 (array size of L antennas) 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                 Isolator-Protected 
                 −52.3 
                 12 
                 L 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Isolator-Free 
                 −48.2 
                 −46.2 
                 −45.1 
                 21 
                 21*4 → 84 
                 0 
               
               
                 Interleaved 
                 [−52.3, −51.2] 
                 [−52.3, −50.8] 
                 [−52.3, −50.2] 
                 12, 21 
                 16.5 
                 ½ L 
               
               
                   
               
            
           
         
       
     
     Notably, under the interleaved antenna configuration, the ACLR may vary in a range. For example, the ACLR of Antenna array #1 can vary between −52.3 dBc and 51.2 dBc. This is because different antenna elements in an antenna array may experience different coupling as a result of respective physical location in the antenna array. It should also be noted that the simulations are performed based on the following assumptions:
         i. Same power amplifier is used for all simulations.   ii. In the case of an isolator-protected antenna array configuration, the same ACLR is achievable for all antenna arrays as coupling plays no role. This also applies to the isolated antenna paths in the interleaved antenna array configuration.   iii. Effective number of DPD coefficients for the number of iterations needed to converge in the DPD coefficient estimation process, which is found to be four (4) for DI-PA DPD in the case of isolator-free antenna array configuration and one (1) in the case of isolator-protected antenna array configuration and interleaved antenna array configuration.   iv. In case the ACLR threshold is set to be −50 dBc (e.g., −45 dBc for mid-band (e.g., sub-6 GHz) transmitters as set by 3GPP plus a +5 dB margin for noise and other effect), it may be concluded that the isolator-free antenna array configuration is not capable of meeting the ACLR threshold.       

     In a non-limiting example, the antenna elements  204 ( 1 )- 204 ( 9 ) in the antenna array  202  are each configured to radiate in a polarization (e.g., horizontal or vertical). However, in some implementations, it may be desirable for the radio node  200  to be able to radiate in more than one polarization. In this regard, the radio node  200  can be configured to include a second antenna array to radiate in a second polarization that is different from the polarization of the antenna array  202 .  FIG.  5    is a schematic diagram of an exemplary antenna array  500  (also referred to as “second antenna array”) having a different polarization from the antenna array  202  in  FIG.  2 A  and configured according to the interleaved configuration of the present disclosure. Common elements between  FIGS.  2 A and  5    are shown therein with common element numbers and will not be re-described herein. 
     The antenna array  500  includes a plurality of non-isolated antenna elements  502 ( 1 ),  502 ( 3 ),  502 ( 5 ),  502 ( 7 ),  502 ( 9 ) and a plurality of isolated antenna elements  502 ( 2 ),  502 ( 4 ),  502 ( 6 ),  502 ( 8 ) that are disposed based on the interleaved antenna array configuration as described in  FIG.  2 A . Similar to the isolated antenna elements  204 ( 2 ),  204 ( 4 ),  204 ( 6 ),  204 ( 8 ) in  FIG.  2 A , the isolated antenna elements  502 ( 2 ),  502 ( 4 ),  502 ( 6 ),  502 ( 8 ) are each coupled to and protected by a respective second antenna isolator  504 . 
     Each of the isolated antenna elements in the antenna array  500  is coupled to a respective second isolated amplifier circuit  506 . The second isolated amplifier circuit  506  may be identical to the isolated amplifier circuit  206  in  FIG.  2 A  and thus will not be re-described herein for the sake of brevity. Likewise, each of the non-isolated antenna elements in the antenna array  500  is coupled to a respective second non-isolated amplifier circuit  508 . The second non-isolated amplifier circuit  508  may be identical to the non-isolated amplifier circuit  208  in  FIG.  2 A  and thus will not be re-described herein for the sake of brevity. 
     In a non-limiting example, the antenna array  200  of  FIG.  2 A  and the second antenna array  500  of  FIG.  5 A  can be stacked to form a dual-polarization antenna array. In this regard,  FIG.  6 A  is a schematic diagram of an exemplary radio node  600  including a dual-polarization antenna array  602  that is formed by stacking the antenna array  202  in  FIG.  2 A  and the antenna array  500  in  FIG.  5   . Common elements between  FIGS.  2 A,  5 , and  6 A  are shown therein with common element numbers and will not be re-described herein. In a non-limiting example, the dual-polarization antenna array  602  can be configured to radiate in both horizontal and vertical polarizations. 
       FIG.  6 B  is an exemplary cross-section view of the dual-polarization antenna array  602  along a cross-section line  604  in  FIG.  6 A . Common elements between  FIGS.  2 A,  5 ,  6 A, and  6 B  are shown therein with common element numbers and will not be re-described herein. 
     In a non-limiting example, the antenna array  202  and the second antenna array  500  are so configured to ensure that the non-isolated antenna element  204 ( 8 ) in the antenna array  202  is stacked on the second non-isolated antenna element  502 ( 8 ) in the second antenna array  600 . Similarly, each of the non-isolated antenna elements  204 ( 7 ),  204 ( 9 ) in the antenna array  202  are stacked on respective second isolated antenna elements  502 ( 7 ),  502 ( 9 ) in the second antenna array  500 . 
       FIG.  6 C  is a schematic diagram of an exemplary radio node  606  including a dual-polarization antenna array  608  that is formed by stacking two antenna arrays according to an alternative configuration.  FIG.  6 D  is an exemplary cross-section view of the dual-polarization antenna array  608  along a cross-section line  610  in  FIG.  6 C . As shown in  FIG.  6 D , the dual-polarization antenna array  608  includes a first antenna array  612  stacked on a second antenna array  614 . In one non-limiting example, each of the first antenna array  612  and the second antenna array  614  has an identical interleaved configuration as in the antenna array  202  of  FIG.  2 A  but with different polarizations. In this regard, when the first antenna array  612  and the second antenna array  614  are stacked, each of the isolated antenna elements  204 ( 8 ) in the first antenna array  612  is stacked on a respective one of the isolated antenna elements  204 ( 8 ) in the second antenna array  614 . Likewise, each of the non-isolated antenna elements  204 ( 7 ),  204 ( 9 ) in the first antenna array  612  is stacked on a respective one of the non-isolated antenna elements  204 ( 7 ),  204 ( 9 ) in the second antenna array  614 . 
       FIG.  7    illustrates one example of a cellular communications network  700  in which embodiments of the present disclosure may be implemented to provide the radio node  200  of  FIG.  2 A , the radio node  236  of  FIG.  2 B , and the radio node  600  of  FIG.  6 A . In the embodiments described herein, the cellular communications network  700  is a 5G NR network. In this example, the cellular communications network  700  includes base stations  702 - 1  and  702 - 2 , which in LTE are referred to as eNBs and in 5G NR are referred to as gNBs, controlling corresponding macro cells  704 - 1  and  704 - 2 . The base stations  702 - 1  and  702 - 2  are generally referred to herein collectively as base stations  702  and individually as base station  702 . Likewise, the macro cells  704 - 1  and  704 - 2  are generally referred to herein collectively as macro cells  704  and individually as macro cell  704 . The cellular communications network  700  may also include a number of low power nodes  706 - 1  through  706 - 4  controlling corresponding small cells  708 - 1  through  708 - 4 . The low power nodes  706 - 1  through  706 - 4  can be small base stations (such as pico or femto base stations) or Remote Radio Heads (RRHs), or the like. Notably, while not illustrated, one or more of the small cells  708 - 1  through  708 - 4  may alternatively be provided by the base stations  702 . The low power nodes  706 - 1  through  706 - 4  are generally referred to herein collectively as low power nodes  706  and individually as low power node  706 . Likewise, the small cells  708 - 1  through  708 - 4  are generally referred to herein collectively as small cells  708  and individually as small cell  708 . The base stations  702  (and optionally the low power nodes  706 ) are connected to a core network  710 . 
     The base stations  702  and the low power nodes  706  provide service to wireless devices  712 - 1  through  712 - 5  in the corresponding cells  704  and  708 . The wireless devices  712 - 1  through  712 - 5  are generally referred to herein collectively as wireless devices  712  and individually as wireless device  712 . The wireless devices  712  are also sometimes referred to herein as UEs. In a non-limiting example, any of the base stations  702 - 1  and  702 - 2  and/or any of the low power nodes  706 - 1  through  706 - 4  can be configured to function as the radio node  200  in  FIG.  2 A , the radio node  236  of  FIG.  2 B , or the radio node  600  in  FIG.  6 A  to enable the interleaved antenna array configuration as described in  FIGS.  2 A and  4   . 
       FIG.  8    is a schematic block diagram of a radio access node  800  according to some embodiments of the present disclosure. The radio access node  800  may be, for example, the radio node  200  of  FIG.  2 A , the radio node  236  of  FIG.  2 B , or the radio node  600  of  FIG.  6 A . As illustrated, the radio access node  800  includes a control system  802  that includes one or more processors  804  (e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and/or the like), a memory  806 , and a network interface  808 . The one or more processors  804  are also referred to herein as processing circuitry. In addition, the radio access node  800  includes one or more radio units  810  that each includes one or more transmitters  812  and one or more receivers  814  coupled to one or more antennas  816 . The radio units  810  may be referred to or be part of radio interface circuitry. In some embodiments, the radio unit(s)  810  is external to the control system  802  and connected to the control system  802  via, e.g., a wired connection (e.g., an optical cable). However, in some other embodiments, the radio unit(s)  810  and potentially the antenna(s)  816  are integrated together with the control system  802 . The one or more processors  804  operate to provide one or more functions of the radio access node  800  as described herein. In some embodiments, the function(s) are implemented in software that is stored, e.g., in the memory  806  and executed by the one or more processors  804 . 
       FIG.  9    is a schematic block diagram of the radio access node  800  of  FIG.  8    according to some other embodiments of the present disclosure. The radio access node  800  includes one or more modules  900 , each of which is implemented in software. The module(s)  900  provides the functionality of the radio access node  800  described herein. 
       FIG.  10    is a schematic block diagram that illustrates a virtualized embodiment of the radio access node  800  of  FIG.  8    according to some embodiments of the present disclosure. This discussion is equally applicable to other types of network nodes. 
     Further, other types of network nodes may have similar virtualized architectures. As used herein, a “virtualized” radio access node is an implementation of the radio access node  800  in which at least a portion of the functionality of the radio access node  800  is implemented as a virtual component(s) (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)). As illustrated, in this example, the radio access node  800  includes the control system  802  that includes the one or more processors  804  (e.g., CPUs, ASICs, FPGAs, and/or the like), the memory  806 , the network interface  808 , and the one or more radio units  810  that each include the one or more transmitters  812  and the one or more receivers  814  coupled to the one or more antennas  816 , as described above. The control system  802  is connected to the radio unit(s)  810  via, for example, an optical cable or the like. The control system  802  is connected to one or more processing nodes  1000  coupled to or included as part of a network(s)  1002  via the network interface  808 . Each processing node  1000  includes one or more processors  1004  (e.g., CPUs, ASICs, FPGAs, and/or the like), a memory  1006 , and a network interface  1008 . 
     In this example, functions  1010  of the radio access node  800  described herein are implemented at the one or more processing nodes  1000  or distributed across the control system  802  and the one or more processing nodes  1000  in any desired manner. In some particular embodiments, some or all of the functions  1010  of the radio access node  800  described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual environment(s) hosted by the processing node(s)  1000 . As will be appreciated by one of ordinary skill in the art, additional signaling or communication between the processing node(s)  1000  and the control system  802  is used in order to carry out at least some of the desired functions  1010 . Notably, in some embodiments, the control system  802  may not be included, in which case the radio unit(s)  810  communicates directly with the processing node(s)  1000  via an appropriate network interface(s). 
     In some embodiments, a computer program including instructions which, when executed by at least one processor, cause the at least one processor to carry out the functionality of the radio access node  800  or a node (e.g., a processing node  1000 ) implementing one or more of the functions  1010  of the radio access node  800  in a virtual environment according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory). 
       FIG.  11    is a schematic block diagram of a UE  1100  according to some embodiments of the present disclosure. As illustrated, the UE  1100  includes one or more processors  1102  (e.g., CPUs, ASICs, FPGAs, and/or the like), a memory  1104 , and one or more transceivers  1106  each including one or more transmitters  1108  and one or more receivers  1110  coupled to one or more antennas  1112 . The transceiver(s)  1106  includes radio-front end circuitry connected to the antenna(s)  1112  that is configured to condition signals communicated between the antenna(s)  1112  and the processor(s)  1104 , as will be appreciated by one of ordinary skill in the art. The processors  1104  are also referred to herein as processing circuitry. The transceivers  1106  are also referred to herein as radio circuitry. In some embodiments, the functionality of the UE  1100  described above may be fully or partially implemented in software that is, e.g., stored in the memory  1104  and executed by the processor(s)  1102 . Note that the UE  1100  may include additional components not illustrated in  FIG.  11    such as, e.g., one or more user interface components (e.g., an input/output interface including a display, buttons, a touch screen, a microphone, a speaker(s), and/or the like and/or any other components for allowing input of information into the UE  1100  and/or allowing output of information from the UE  1100 ), a power supply (e.g., a battery and associated power circuitry), etc. 
     In some embodiments, a computer program is provided including instructions which, when executed by at least one processor, cause the at least one processor to carry out the functionality of the UE  1100  according to any of the embodiments described herein. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory). 
       FIG.  12    is a schematic block diagram of the UE  1100  of  FIG.  11    according to some other embodiments of the present disclosure. The UE  1100  includes one or more modules  1200 , each of which is implemented in software. The module(s)  1200  provides the functionality of the UE  1200  described herein. 
     At least some of the following abbreviations may be used in this disclosure. If there is an inconsistency between abbreviations, preference should be given to how it is used above. If listed multiple times below, the first listing should be preferred over any subsequent listing(s).
         3G Third Generation   3GPP Third Generation Partnership Project   4G Fourth Generation   5G Fifth Generation   5G-NR Fifth Generation-New Radio   ACLR Adjacent Channel Leakage Ratio   AMF Access and Mobility Function   ASIC Application Specific Integrated Circuit   AUSF Authentication Server Function   BS Base Station   CPU Central Processing Unit   DI-PA Dual-Input Power Amplifier   DPD Digital Predistortion   eNB Enhanced or Evolved Node B   FPGA Field Programmable Gate Array   gNB New Radio Base Station   gNB-DU New Radio Base Station Distributed Unit   HSS Home Subscriber Server   IoT Internet of Things   LTE Long Term Evolution   MIMO Multiple Input Multiple Output   MME Mobility Management Entity   mm-wave Millimeter Wave   MTC Machine Type Communication   MU Multi-User   NEF Network Exposure Function   NF Network Function   NR New Radio   NRF Network Function Repository Function   NSSF Network Slice Selection Function   PC Personal Computer   PCF Policy Control Function   P-GW Packet Data Network Gateway   RAN Radio Access Network   RAT Radio Access Technology   RF Radio Frequency   SCEF Service Capability Exposure Function   SISO Single Input Single Output   SMF Session Management Function   TDD Time Division Duplexing   UDM Unified Data Management   UE User Equipment   UPF User Plane Function       

     Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.