Patent Publication Number: US-11381264-B2

Title: System-aware RF front ends for wireless communication systems

Description:
RELATED APPLICATIONS 
     This application claims the benefit of provisional patent application Ser. No. 62/985,386, filed Mar. 5, 2020, the disclosure of which is hereby incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure is related to radio frequency (RF) front ends. 
     BACKGROUND 
     In traditional radio frequency (RF) communications systems, an RF front end includes receive (RX) and transmit (TX) chains as well as appropriate filters, switches, n-plexors, tuners, etc., which connect to an antenna or antenna sub-systems. The complexity of these RF front end chains is growing rapidly, irrespective of the applications at hand. For example, in automotive applications, the motivation of end manufacturers is to reduce the overall number of elements needed in order to miniaturize the form factor of RF transceiver and antenna devices (e.g., frequently deployed in a shark fin). Likewise, in fifth generation (5G) infrastructure, the motivation is to reduce thermal issues in both power amplifiers on the TX chain and low noise amplifiers on the RX chain. 
       FIG. 1  is a schematic block diagram of a traditional infrastructure remote radio unit (RRU)  10 . The illustrated example is a 5G new radio (NR) communication system  12 , with the RRU  10  connected via various back-haul units  14  to a central baseband unit  16 . Historically, to avoid complex control protocols, the RRU  10  receives a very limited amount of control information from the central baseband unit  16 . In particular, such control information is concentrated in layer 1 media access control (MAC)/physical layer (PHY) circuitry  18  and a transceiver device  20 . 
     A traditional RF front end  22  receives, amplifies, and forwards RF TX and RX signals. Thus, the traditional RF front end  22  does not receive control information or have awareness of the other components of the 5G NR communication system  12 . Thus, the control interface from either the central baseband unit  16  or the transceiver device  20  to the traditional RF front end  22  tends to be sparse at best. This does not allow for potential optimizations that are feasible with a complex communication system, such as 5G-NR. 
     SUMMARY 
     System-aware radio frequency (RF) front ends for wireless communication systems are provided. High complexity communication systems, such as Third Generation Partnership Project (3GPP) fifth generation (5G)-new radio (NR) systems, impose severe board area, volume, thermal and interference penalties on wireless devices. In the case of 5G-NR, this is due to the number of bands to be supported, the instantaneous bandwidth and spectral efficiency among other parameters. Other communications systems can involve high modulation of other parameters that similarly impose such penalties. Embodiments described herein provide a co-designed RF front end architecture that utilizes system knowledge (e.g., from baseband or other digital control circuitry, from antenna feedback, etc.) to dynamically adjust the parameters of various RF front-end components. System-aware RF front ends are thus able to improve and optimize performance criteria (e.g., to reduce the above penalties in complex communications systems). 
     An exemplary embodiment provides a system-aware RF front end. The system-aware RF front end includes a transmit (TX) node configured to receive an RF TX signal from a transceiver, a receive (RX) node configured to transmit an RF RX signal to the transceiver, and an antenna node configured to couple to an RF antenna. The system-aware RF front end further includes at least one RF power amplifier (PA) coupled between the TX node and the antenna node. The system-aware RF front end further includes at least one RF low noise amplifier (LNA) coupled between the RX node and the antenna node. The system-aware RF front end further includes a processor configured to receive meta information from control circuitry and process the meta information to determine a control scheme for the system-aware RF front end based on the meta information. 
     Another exemplary embodiment provides a method for controlling a RF front end using system information. The method includes receiving meta information for a wireless communication system from a plurality of data sources external to the RF front end. The method further includes processing, with a processor local to the RF front end, the meta information and determining a control scheme for the RF front end based on the processed meta information. 
     Another exemplary embodiment provides a RF device. The RF device includes RF system control circuitry and a transceiver configured to provide an RF TX signal from an upstream TX signal received from the RF system control circuitry and provide an upstream RX signal to the RF system control circuitry from an RF RX signal. The RF device further comprises a RF front end module coupled between the transceiver and an antenna, the RF front end module comprising a processor configured to receive meta information from the RF system control circuitry and process the meta information to determine a control scheme for the RF front end module based on the meta information. 
     Those skilled in the art will appreciate the scope of the present disclosure and realize additional aspects thereof after reading the following detailed description of the preferred embodiments in association with the accompanying drawing figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       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  is a schematic block diagram of a traditional infrastructure remote radio unit (RRU). 
         FIG. 2  is a schematic block diagram of a radio frequency (RF) device which includes a system-aware RF front end according to embodiments described herein. 
         FIG. 3  is a schematic block diagram of the system-aware RF front end of  FIG. 2  according to an exemplary aspect. 
         FIG. 4  is a schematic block diagram of a RF device with multiple RF front end modules according to another exemplary aspect. 
         FIG. 5  is a schematic block diagram of a RRU according to another exemplary aspect. 
         FIG. 6  is a flow diagram of a process for controlling a RF front end using system information. 
         FIG. 7  is a block diagram of a processor suitable for controlling a RF front end according to embodiments disclosed herein. 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments set forth below represent the necessary 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 and the accompanying claims. 
     It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that when an element such as a layer, region, or substrate is referred to as being “on” or extending “onto” another element, it can be directly on or extend directly onto the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” or extending “directly onto” another element, there are no intervening elements present. Likewise, it will be understood that when an element such as a layer, region, or substrate is referred to as being “over” or extending “over” another element, it can be directly over or extend directly over the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly over” or extending “directly over” another element, there are no intervening elements present. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. 
     Relative terms such as “below” or “above” or “upper” or “lower” or “horizontal” or “vertical” may be used herein to describe a relationship of one element, layer, or region to another element, layer, or region as illustrated in the Figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including” when used herein specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     System-aware radio frequency (RF) front ends for wireless communication systems are provided. High complexity communication systems, such as Third Generation Partnership Project (3GPP) fifth generation (5G)-new radio (NR) systems, impose severe board area, volume, thermal and interference penalties on wireless devices. In the case of 5G-NR, this is due to the number of bands to be supported, the instantaneous bandwidth and spectral efficiency among other parameters. Other communications systems can involve high modulation of other parameters that similarly impose such penalties. Embodiments described herein provide a co-designed RF front end architecture that utilizes system knowledge (e.g., from baseband or other digital control circuitry, from antenna feedback, etc.) to dynamically adjust the parameters of various RF front-end components. System-aware RF front ends are thus able to improve and optimize performance criteria (e.g., to reduce the above penalties in complex communications systems). 
       FIG. 2  is a schematic block diagram of a RF device  24  which includes a system-aware RF front end  26  according to embodiments described herein. In an exemplary aspect, embodiments provide a system architecture that facilitates communication back and forth between digital baseband, transceiver, and RF sub-systems in order to achieve optimization in different metrics. Certain embodiments also use these parameters towards optimization of certain components of the system-aware RF front end  26 . 
     In this regard, the RF device  24  includes a transceiver  28  with RF transmit (TX) circuitry  30  and RF receive (RX) circuitry  32  for sending and receiving RF signals. The transceiver  28  transmits and receives RF signals. In an exemplary aspect, RF system control circuitry  34  provides an upstream TX signal TXUS (e.g., a baseband signal) to the RF TX circuitry  30 . The RF TX circuitry  30  processes the upstream TX signal TXUS to provide an RF TX signal RFTXS to be transmitted over one or more antennas  36 . The RF TX circuitry  30  may include up-conversion circuitry, amplification circuitry, power supply circuitry, filtering circuitry, switching circuitry, combining circuitry, splitting circuitry, dividing circuitry, clocking circuitry, the like, or any combination thereof to process the upstream TX signal TXUS. 
     The RF RX circuitry  32  receives and processes an RF RX signal RFRXS from the one or more antennas  36  to provide an upstream RX signal RXUS (e.g., a baseband signal). The RF RX circuitry  32  may include down-conversion circuitry, amplification circuitry, low noise amplification circuitry, power supply circuitry, filtering circuitry, switching circuitry, combining circuitry, splitting circuitry, dividing circuitry, clocking circuitry, the like, or any combination thereof. 
     The system-aware RF front end  26  receives, amplifies, and routes the RF TX signal RFTXS from the RF TX circuitry  30  to the one or more antennas  36 . In addition, the system-aware RF front end  26  further receives, routes, and amplifies signals received via the one or more antennas  36  as the RF RX signal RFRXS to the RF RX circuitry  32 . In some examples, additional circuitry, such as tuning and filtering circuitry  38 , can be coupled between the system-aware RF front end  26  and the one or more antennas  36 . In some embodiments, the tuning and filtering circuitry  38  is considered part of the system-aware RF front end  26 . 
     In an exemplary aspect, the system-aware RF front end  26  includes a processor  40  which communicates with other components of the RF device  24  via an information bus  42 . The information bus  42  can be an appropriate information bus for sending and receiving meta information and/or control information which extends beyond traditional control schemes. In an exemplary aspect, the system-aware RF front end  26  is an integrated circuit which includes the processor  40  (e.g., with associated memory and control circuitry), an RX chain, and a TX chain. 
     The processor  40  can receive and process one or more parameters in 5G-NR and other communications systems to better optimize operation of the system-aware RF front end  26 . Examples of such parameters include, but are not limited to:
         Variable sub-carrier spacing (e.g., varying between 15 and 240 kilohertz (kHz))   Symbol load tracking   Flexible frame structure   Dynamic modulation information   System quality of service (QoS) indication   Resource block (RB) indication (e.g., dynamic RB indication)   Signal quality indicator (SQI)   Beamforming codebook   Channel state matrix (e.g., multiple input multiple output (MIMO) matrix)       

     Each of the above parameters are high level parameters that are intended to be fed to a front-end system. The information bus  42  facilitates exchanging information between some or all of the RF system control circuitry  34  (which may provide baseband parameters and/or control information), the transceiver  28 , the system-aware RF front end  26 , and the tuning and filtering circuitry  38 . The illustrated system architecture prevents overloading traditional interface structures. 
     In further detail,  FIG. 3  is a schematic block diagram of the system-aware RF front end  26  of  FIG. 2  according to an exemplary aspect. The system-aware RF front end  26  may be deployed in any appropriate RF device  24 , such as a user equipment (UE) or a remote radio unit (RRU) in a 5G-NR system, a WiFi device, a cellular phone, a computer, or any other device configured to communicate via an RF communications system. 
     The system-aware RF front end  26  includes a TX chain  44 , which includes one or more RF power amplifiers (PAs) coupled between a TX node (TX, which is coupled to the transceiver  28 ) and an antenna node (ANT, which is coupled to an antenna  36 ). The TX chain  44  can include additional TX signal conditioning circuitry, such as filtering circuitry. The system-aware RF front end  26  further includes a RX chain  46 , which includes one or more low noise amplifiers coupled between a RX node (RX, which is coupled to the transceiver  28 ) and the antenna node. The RX chain  46  can include additional RX signal conditioning circuitry, such as filtering circuitry. 
     The system-aware RF front end  26  can include or be coupled to a tuner  48  and one or more filters  50 . In some examples, the tuner  48  may include a circulator, a diplexer, multiplexer, switching circuitry, etc., to facilitate coupling the TX chain  44  and the RX chain  46  to a common antenna  36 . 
     In an exemplary aspect, the information bus  42  is a MIPI RF front end interface, which may be modified as further described herein. Through the information bus  42 , the processor  40  (which includes a memory) can receive and process meta information from the transceiver  28 , from baseband circuitry (not shown), from the tuner  48 , or from the filters  50 . The processor  40  then uses the meta information to determine a control scheme for the system-aware RF front end  26  (e.g., to adjust one or more parameters, such as an impedance in the TX chain  44  or the RX chain  46 , an input power or gain of one or more RF PAs, phase adjustment circuitry, enabling or disabling one or more of an array of RF PAs, etc.). 
     As used herein, “meta information” refers to indirect information which can be relevant to the RF signals processed by the system-aware RF front end  26  (i.e., information other than the RF signals themselves). For example, the information bus  42  may provide the processor  40  with meta information regarding communication system conditions (e.g., radio conditions) received from the transceiver  28  or baseband circuitry in order to optimize performance of the system-aware RF front end  26 . For example, the communication system condition can be an interference measurement, such as reference signal received power (RSRP), and the control scheme determined by the processor  40  can adjust an input power of one or more RF PAs to reduce interference (and/or conserve power when less interference is present). As another example, the processor  40  can be coupled to a sensor that can detect an output RF condition at the antenna node (e.g., an impedance sensor  52  sensing impedance at the antenna node, or a power detector, phase detector, etc.), which can be used to compensate for the output RF condition (e.g., perform dynamic impedance matching) in the system-aware RF front end  26 . 
     The system-aware RF front end  26  architecture described herein allows for high level parameters to be available to both the TX chain  44  and the RX chain  46  in the form of parameters from both the digital baseband and observation parameters from the antenna. The incorporation of the processor  40  (e.g., a processing and storage engine, which can include a number of different processing and memory components as further described below with respect to  FIG. 7 ) allows for self-standing and independent computations to be performed and control signals propagated effectively to the TX chain  44  and the RX chain  46 . 
     Representative and non-exhaustive examples of the types of meta information that can be obtained, along with optimizations that can be made using different control schemes of the system-aware RF front end  26  are listed below:
         Variable sub-carrier spacing (e.g., varying between 15 and 240 kHz)
           PA linearity performance optimization; Filter transition regions may be relaxed   
           Symbol load tracking
           Symbol based envelope tracking techniques for PA efficiency enhancement   
           Flexible frame structure
           Potential adjacent channel leakage ratio (ACLR) relaxation based on dynamic frame information   
           Dynamic modulation information
           Linearity relaxation in a dynamic fashion (and thus power consumption improvement)   
           System QoS indication
           Bias and power optimization based on QoS for both receive and transmit links   
           RB indication (e.g., dynamic RB indication)
           Allows for filter transition region relaxation and/or insertion loss optimization   
           SQI
           Power optimization on the receive side   Likewise, power and linearity optimization on the transmit side of the link   
           Beamforming codebook   Channel state matrix (e.g., MIMO matrix)
           Dynamic adjustment of per chain power amplifier dynamics for overall RRU/UE optimization   
               

       FIG. 4  is a schematic block diagram of a RF device  24  with multiple RF front end modules  54  according to another exemplary aspect. The RF device  24  may be a MIMO device which includes multiple RF front end modules  54 , each having a corresponding antenna array. The RF device  24  includes baseband circuitry  56  (which may correspond to the RF system control circuitry  34  of  FIG. 2 ), which can receive meta information from an upstream source in the RF communication system (e.g., a central baseband unit, a higher level application, etc.). The baseband circuitry  56  includes baseband communication circuitry  58  which provides the meta information to each of the RF front end modules  54  via the information bus  42 . 
     In this regard, each RF front end module  54  includes a corresponding processor  40 , which receives and processes the meta information. Each processor  40  then separately determines a control scheme which is appropriate to the signals and radio environment pertaining thereto. In some embodiments, the RF front end modules  54  may further exchange meta information with one another, such as information about the control scheme each is using, to further enhance performance of the RF device  24  overall. 
       FIG. 5  is a schematic block diagram of a RRU  60  according to another exemplary aspect. The RRU  60  includes multiple transceivers  28 , each of which may in turn include multiple RF front end modules  54 . As with the above embodiments, each of the RF front end modules  54  includes a corresponding processor  40  which provides system awareness to enhance performance. 
       FIG. 6  is a flow diagram illustrating a process for controlling a RF front end using system information. The process begins at operation  600 , with receiving meta information for a wireless communication system from a plurality of data sources external to the RF front end. The process continues at operation  602 , with processing, with a processor local to the RF front end (e.g., the processor  40  of  FIG. 2 ), the meta information. The process continues at operation  604 , with determining a control scheme for the RF front end based on the processed meta information. 
     Although the operations of  FIG. 6  are illustrated in a series, this is for illustrative purposes and the operations are not necessarily order dependent. Some operations may be performed in a different order than that presented. Further, processes within the scope of this disclosure may include fewer or more steps than those illustrated in  FIG. 6 . 
       FIG. 7  is a block diagram of a processor  40  suitable for controlling a RF front end according to embodiments disclosed herein. The processor  40  includes or is implemented as a computer system  700 , which comprises any computing or electronic device capable of including firmware, hardware, and/or executing software instructions that could be used to perform any of the methods or functions described above, such as controlling a RF front end using system information (e.g., meta information). In this regard, the computer system  700  may be a circuit or circuits included in an electronic board card, such as a printed circuit board (PCB), a server, a personal computer, a desktop computer, a laptop computer, an array of computers, a personal digital assistant (PDA), a computing pad, a mobile device, or any other device, and may represent, for example, a server or a user&#39;s computer. 
     The exemplary computer system  700  in this embodiment includes a processing device  702  or processor, a system memory  704 , and a system bus  706 . The system memory  704  may include non-volatile memory  708  and volatile memory  710 . The non-volatile memory  708  may include read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and the like. The volatile memory  710  generally includes random-access memory (RAM) (e.g., dynamic random access memory (DRAM), such as synchronous DRAM (SDRAM)). A basic input/output system (BIOS)  712  may be stored in the non-volatile memory  708  and can include the basic routines that help to transfer information between elements within the computer system  700 . 
     The system bus  706  provides an interface for system components including, but not limited to, the system memory  704  and the processing device  702 . The system bus  706  may be any of several types of bus structures that may further interconnect to a memory bus (with or without a memory controller), a peripheral bus, and/or a local bus using any of a variety of commercially available bus architectures. 
     The processing device  702  represents one or more commercially available or proprietary general-purpose or application-specific processing devices, such as a microprocessor, central processing unit (CPU), an application-specific integrated circuit (ASIC) or the like. More particularly, the processing device  702  may be a complex instruction set computing (CISC) microprocessor, a reduced instruction set computing (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, a processor implementing other instruction sets, or other processors implementing a combination of instruction sets. The processing device  702  is configured to execute processing logic instructions for performing the operations and steps discussed herein. 
     In this regard, the various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with the processing device  702 , which may be a microprocessor, field programmable gate array (FPGA), a digital signal processor (DSP), an ASIC, or other programmable logic device, a discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. Furthermore, the processing device  702  may be a microprocessor, or may be any conventional processor, controller, microcontroller, or state machine. The processing device  702  may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration). 
     An operating system  714  and any number of program modules  716  or other applications can be stored in the volatile memory  710 , wherein the program modules  716  represent a wide array of computer-executable instructions corresponding to programs, applications, functions, and the like that may implement the functionality described herein in whole or in part, such as through instructions  718  on the processing device  702 . All or a portion of the functionality described herein may be implemented as a computer program product stored on a transitory or non-transitory computer-usable or computer-readable storage medium, such as the volatile memory  710 , non-volatile memory  708 , instructions  718 , and the like. The computer program product includes complex programming instructions, such as complex computer-readable program code, to cause the processing device  702  to carry out the steps necessary to implement the functions described herein. 
     The computer system  700  may further include a communication interface  720 . The communication interface  720  may facilitate communications with any number of devices, such as via the information bus  42 . Additional inputs and outputs to the computer system  700  may be provided through the system bus  706  as appropriate to implement embodiments described herein. 
     The operational steps described in any of the exemplary embodiments herein are described to provide examples and discussion. The operations described may be performed in numerous different sequences other than the illustrated sequences. Furthermore, operations described in a single operational step may actually be performed in a number of different steps. Additionally, one or more operational steps discussed in the exemplary embodiments may be combined. 
     Those skilled in the art will recognize improvements and modifications to the preferred embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.