Patent Publication Number: US-11664835-B2

Title: Fully integrated radio frequency terminal system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 16/469,123, entitled “Fully Integrated Radio Frequency Terminal System,” filed on Jun. 12, 2019, which is a U.S. national stage of International PCT Application No. PCT/US2017/067995, filed on Dec. 21, 2017, which claims the benefit and priority of U.S. Provisional Patent Application No. 62/536,356, titled “Fully Integrated RF Terminal,” filed on Jul. 24, 2017 and also claims the benefit and priority of U.S. Provisional Patent Application No. 62/438,371, titled “Fully Integrated Radio Frequency System,” filed on Dec. 22, 2016, the entire contents of all applications are hereby incorporated by reference herein. 
    
    
     BACKGROUND 
     1. Field 
     The present disclosure generally relates radio frequency communication systems. 
     2. Description of the Related Art 
     Radio frequency communication systems have evolved on architecture based on the limits of contemporary hardware design. This has resulted in systems that do not take full advantage of advances in radio frequency and digital circuit integration and miniaturization. In particular, digital modulation and demodulation (modem) functions have traditionally been separated from radio frequency conversion and amplification functions. This allowed the previously large and complex modem functions to reside at the user end of the system in a more protected environment. 
     Conventionally, only those functions which required low loss direct connection to the antenna (e.g., transmission power amplifier, receive low noise amplifier) were placed at the antenna. The interface between modem and antenna electronics was accomplished with fixed tuned block converters mounted near the antenna to convert the high radio frequency frequencies to a lower intermediate frequency band. Relatively long broadband intermediate frequency cables provided the link between antenna mounted electronics and the modem. 
     This architecture was created when a modem was implemented as a large chassis full of analog and digital electronics, but has significant disadvantages. Accordingly, there is a need for an improved system. 
     SUMMARY 
     Disclosed herein is an integrated radio frequency terminal system. The system includes an integrated modem. The integrated modem includes a baseband modem device configured to receive user data and communicate user data to and from a user device via a digital interface cable. The integrated modem also includes a transmit tuner connected to the baseband modem device and configured to receive the user data and convert the user data from baseband to an intermediate frequency band. The integrated modem also includes a receive tuner connected to the baseband modem device and configured to convert received incoming data in an intermediate frequency band to baseband and provide the converted incoming data to the baseband modem device. The system also includes a power amplifier connected to the integrated modem and configured to convert the user data from the intermediate frequency band to a radio frequency band. The system also includes a low noise amplifier connected to the integrated modem and configured to convert received incoming data from the radio frequency band to the intermediate frequency band. 
     Also disclosed is an integrated radio frequency terminal system. The system includes an integrated modem. The integrated modem includes a baseband modem device configured to receive user data and communicate user data to and from a user device via a digital interface cable. The integrated modem includes a transmit tuner connected to the baseband modem device and configured to receive the user data and convert the user data from baseband to a radio frequency band without converting to an intermediate frequency band. The integrated modem includes a receive tuner connected to the baseband modem device and configured to convert received incoming data in the radio frequency band to baseband without converting to an intermediate frequency band and provide the converted incoming data to the baseband modem device. The system includes an antenna device connected to the integrated modem and configured to transmit the user data in the radio frequency band and receive the incoming data in the radio frequency band. 
     Also disclosed is a method of transmitting user data. The method includes receiving, by an integrated modem located proximal to an antenna device, user data in baseband frequency. The method also includes converting, by the integrated modem, the user data from baseband frequency to radio frequency. The method also includes receiving, by the antenna device, the converted user data. The method also includes transmitting, by the antenna device, the converted user data in radio frequency. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other systems, methods, features, and advantages of the present invention will be or will become apparent to one of ordinary skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims. Component parts shown in the drawings are not necessarily to scale, and may be exaggerated to better illustrate the important features of the present invention. In the drawings, like reference numerals designate like parts throughout the different views, wherein: 
         FIG.  1    is an integrated radio frequency terminal system using intermediate frequency conversion according to an embodiment of the present disclosure. 
         FIG.  2    is an integrated radio frequency terminal system using direct conversion according to an embodiment of the present disclosure. 
         FIG.  3    is an integrated radio frequency terminal system using a digital predistortion device according to an embodiment of the present disclosure. 
         FIG.  4    is an integrated radio frequency terminal system using a port expander according to an embodiment of the present disclosure. 
         FIG.  5    is a flowchart of a process of the integrated radio frequency terminal system according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Conventionally, digital modulation and demodulation (modem) functions are separated from radio frequency conversion and amplification functions. This allows the previously large and complex modem functions to reside at the user end of the system in a more protected environment. Accordingly, only those functions which required low loss direct connection to the antenna (e.g., transmission power amplifier and receive low noise amplifier) were placed at the antenna. The interface between modem and antenna electronics was accomplished with fixed tuned block converters mounted near the antenna to convert the high radio frequency frequencies to a lower intermediate frequency band. Long broadband intermediate frequency cables provided the link between antenna mounted electronics and the modem. 
     However, when a modem is capable of being implemented as a single integrated circuit, this conventional architecture becomes unnecessary and has important disadvantages. Use of a fixed broadband intermediate frequency link and separate modem within the conventional radio frequency terminals increases cost and imposes performance limitations. The system described herein integrates all radio frequency functions and modem functions within the terminal to mitigate these disadvantages. By integrating all radio frequency functions and modem functions, intermediate frequency cable links may be removed, and the resulting integrated system may be capable of improved performance. In addition, the system described herein improves size, weight, and power requirements of the system, when compared to conventional systems. 
       FIG.  1    illustrates an example embodiment of the fully integrated radio frequency terminal system, according to an embodiment of the present disclosure. 
     The fully integrated radio frequency terminal system  100  includes an integrated modem  102 , a power amplifier  110 , a low noise amplifier  112 , and an antenna device  114 . The integrated modem  102 , the power amplifier  110 , and the low noise amplifier  112  may be physically located outside and proximal to the antenna device  114 . For example, the integrated modem  102 , the power amplifier  110 , and the low noise amplifier  112  may be located within several feet of the antenna device  114  or may share a common housing. This is different from a conventional system, where a modem is located proximal to the user device, a radio frequency (RF) assembly is located proximal to the antenna device, and intermediate frequency (IF) cables are run between the modem and the RF assembly. These intermediate frequency cables, commonly operating in L-band, may be long and may cause mixer spur issues, as a relatively wide bandwidth must be used. Standardized intermediate frequency bands may also cause issues for some radio frequency bands due to location of higher order mixer spurious products and force use of more conversion stages. Use of L-band also results in difficult mixer spurious issues in IF to Ku (or other frequency) conversion due to wide intermediate frequency bandwidth (BW) (up to 950 to 1700 MHz for wide band TX, up to 950 to 2750 for wideband RX). The L-band systems may involve difficult filters and/or spur cancellation. In addition, L-Band cable losses and frequency response degrade system performance and force wider TX and RX dynamic range to compensate for cable loss variation. Long cable runs may include more expensive low loss cable, in some installations. 
     In some embodiments, the integrated modem  102 , the power amplifier  110 , and the low noise amplifier  112  are within a single housing. In other embodiments, the integrated modem  102  is within a first housing and the power amplifier  110  and the low noise amplifier  112  are within a second housing. In some embodiments, some or all of the antenna device  114  is in the same housing as the integrated modem  102 . In many embodiments, the integrated modem  102 , the power amplifier  110 , and the low noise amplifier  112  are within a housing located outdoors, and the digital interface cable facilitating transmission of the user data  116  terminates indoors, to a user device or a port expander (as shown in  FIG.  4   ). The user device may be a processor, a router and/or a computing device. 
     The integrated modem  102  includes a baseband modem device  104  configured to receive a baseband signal of user data  116 . The user data  116  may be sent to the integrated modem  102  via a digital interface cable, which does not affect transmission performance. Because the integrated modem  102  is located proximal to the antenna device  114 , the digital interface cable may be longer than in previous conventional systems, and the length of the digital interface cable may vary based on context and application. However, cable loss for digital signals is lower than for intermediate frequency cables, so longer cable runs (using digital interface cables versus intermediate frequency cables) are possible without performance deterioration. While digital interface cables are described as being used herein, any digital link approach, including fiber optics, may be used to communicate user data  116 . Power for the system may be sourced near the antenna device  114  or via a separate power cable. 
     The integrated modem  102  also includes a transmit tuner  106  and a receive tuner  108 . The transmit tuner  106  tunes a received baseband signal and converts the baseband signal to an intermediate frequency. The intermediate frequency may be any frequency between the baseband frequency and the radio frequency used by the antenna device  114 . 
     The intermediate frequency signal is then provided to a power amplifier  110 , which converts the intermediate frequency signal to the radio frequency band signals. The radio frequency band signals may have a radio frequency anywhere in the electromagnetic spectrum. In some embodiments, the radio frequency band signals are in the Ku band or higher. The antenna device  114  receives the radio frequency band signals and transmits them via an RF link  118 . The RF link  118 , as used herein, refers to the space between two antenna systems exchanging data (e.g., the antenna device  114  and a corresponding antenna device communicating with the antenna device  114 ). 
     The application of the user data transmission may be digitally configured and adjusted without modifying the physical components of the system  100 . For example, the user data may be transmitted using satellite communications or may be transmitted using terrestrial communications by configuring the transmit tuner  106 . The transmit tuner  106  includes a local oscillator, which may be an adjustable, agile local oscillator configured to provide any number of different waveforms. Thus, the system  100  is not limited to one type of communications. Accordingly, the receive tuner  108  also may have an adjustable, agile local oscillator. 
     In some embodiments, as shown in  FIG.  1   , the transmit tuner  106  and the receive tuner  108  also include a mixer and a bandpass filter. 
     The antenna device  114  may receive data from via the RF link  118  in the radio frequency band, and the antenna device  114  may provide the received data to the low noise amplifier  112  for converting down to an intermediate frequency. The converted data is provided to the receive tuner  108  for further conversion down to baseband, so that the data can be passed to the user device via the baseband modem device  104 . 
     The system  100  converts the baseband to the radio frequency band in two steps: once from the baseband to the intermediate frequency and once from the intermediate frequency to the radio frequency. The intermediate frequency used does not require a high level of bandwidth, as compared to previous systems, as the integrated modem  102  is located nearby the antenna device  114 , and lengthy intermediate frequency cable runs are not used. This reduction in bandwidth used eliminates many of the issues present in conventional systems. By having the various components of the system located proximal to the antenna device  114 , the system is made more efficient, more compact, cheaper to produce, easier to maintain, and lighter. 
       FIG.  2    illustrates an example embodiment of the fully integrated radio frequency terminal system, according to an embodiment of the present disclosure. 
     The system  200  is similar to the system  100 , and like parts are numbered similarly. The system  200  includes an integrated modem  202  located proximal to an antenna device  214 . The integrated modem  202  has a baseband modem device  204  configured to transmit and receive user data  216  to and from a user device. The user device may be a processor, a router or a computing device. 
     The user data  216  received by the integrated modem  202  via the baseband modem device  204  is converted from the baseband to the radio frequency band. This conversion may be accomplished by a transmit tuner  206  or a block upconverter. In some embodiments, a solid state power amplifier is also used. The antenna device  214  receives the user data  216  in radio frequency band, and transmits it via the RF link  218 . 
     The antenna device  214  receives data via the RF link  218  and transmits it to the integrated modem  202 . The received data is converted from the radio frequency band to the baseband. This conversion may be accomplished by a receive tuner  208  or a low noise block downconverter. The baseband modem device  204  receives the data converted to baseband and provides the data to the user device. 
     The integrated modem  202  is located proximal to the antenna device  214  and away from the user device. As a result, the user data  216  is transmitting along a relatively long digital interface cable. As described herein, cable loss for digital signals is lower than for intermediate frequency cables, so longer cable runs are possible without performance deterioration. While digital interface cables are described as being used herein, any digital link approach, including fiber optics, may be used to communicate user data  216 . As described herein, the long digital interface cable being used is preferable to the conventional systems where a long intermediate frequency cable is used. The system  200  minimizes radio frequency losses for best transmission (TX) power efficiency and receiving (RX) noise figure. 
     The system provides a single conversion TX and RX paths (baseband to/from Ku Band). Passive TX reject (in RX path) and RX reject (in TX path) filters and other antenna components may change with application, but electronics are agile across approximately 1 octave bandwidth, limited by local oscillator tuning range and quadrature hybrid performance. 
     Added modem functions may be achieved with less size, weight, and power (SWaP) than is gained by simplifying the TX and RX radio frequency chains, so net SWaP of antenna mounted components is reduced when compared to L-Band intermediate frequency systems. The total cost of the system may be reduced by elimination of separate component assemblies. 
     The system encounters no mixer spurious issues, since wideband intermediate frequency transmission is eliminated. Baseband filtering and pre-distortion are used to meet TX spectrum requirements. RX selectivity is achieved with baseband filtering. Filtering and pre-distortion (as illustrated in  FIGS.  3  and  4   ) can be implemented digitally. 
     The system  200  performs the same functions as the system  100 , but the system  200  does not convert the baseband to any intermediate frequency, but rather converts the baseband directly to the radio frequency band. Depending on the cost of various internal components described herein, the most cost effective solution among the various embodiments of the system may change, but all embodiments of the system are preferable to the conventional system, for the reasons described herein. 
     Similar to the system  100 , the application of the user data transmission may be digitally configured and adjusted without modifying the physical components of the system  200 . For example, the user data may be transmitted using satellite communications or may be transmitted using terrestrial communications by configuring the transmit tuner  206 , which includes an adjustable, agile local oscillator configured to provide any number of different waveforms. Thus, the system  200  is not limited to one type of communications. Accordingly, the receive tuner  208  also may have an adjustable, agile local oscillator. In some embodiments, as shown in  FIG.  2   , the transmit tuner  206  and the receive tuner  208  also include a mixer and a bandpass filter. 
       FIG.  3    illustrates an example embodiment of the fully integrated radio frequency terminal system, according to an embodiment of the present disclosure. The system  300  is similar to the system  100  and the system  200 , and like parts are numbered similarly. 
     The system  300  includes an integrated modem  302 , a power amplifier  310 , a low noise amplifier  312 , and an antenna device  314 . The integrated modem  302 , the power amplifier  310 , and the low noise amplifier  312  may be physically located proximal to the antenna device  314 . As described herein, this is different from a conventional system, where a modem is located proximal to the user device, a radio frequency assembly is located proximal to the antenna device, and IF cables connect the modem and the radio frequency assembly. 
     In some embodiments, the integrated modem  302 , the power amplifier  310 , and the low noise amplifier  312  are within a single housing. In other embodiments, the integrated modem  302  is within a first housing and the power amplifier  310  and the low noise amplifier  312  are within a second housing. In some embodiments, some or all of the antenna device  314  is in the same housing as the integrated modem  302 . 
     The integrated modem  302  includes a baseband modem device  304  configured to receive a baseband signal of user data  316  and transmit a baseband signal of user data  316 . The user data  316  may be sent to the integrated modem  302  via a digital interface cable, which does not affect transmission performance. While digital interface cables are described as being used herein, any digital link approach, including fiber optics, may be used to communicate user data  316 . Power for the system may be sourced near the antenna device  314  or via a separate power cable. 
     The integrated modem  302  includes a digital predistortion device  320  configured to reduce distortion of the user data  316  as it is processed for transmission by the antenna device  314 . The digital predistortion device  320  receives a sample of the data signal after it is converted to the radio frequency band by the transmit tuner  306  and the power amplifier  310 , and the digital predistortion device compensates for distortion detected in the sample, such that distortion in subsequent data is reduced. 
     The integrated modem  302  also includes a transmit tuner  306  and a receive tuner  308 . The transmit tuner  306  tunes a received, digitally predistorted baseband signal and converts the baseband signal to an intermediate frequency. The intermediate frequency signal is then provided to a power amplifier  310 , which converts the intermediate frequency signal to the radio frequency band signals. The antenna device  314  receives the radio frequency band signals and transmits them via an RF link  318 . 
     The antenna device  314  may receive data via the RF link  318  in the radio frequency band, and the antenna device  314  may provide the received data to the low noise amplifier  312  for converting down to an intermediate frequency. The converted data is provided to the receive tuner  308  for further conversion down to baseband, so that the data can be passed to the user device via the baseband modem device  304 . 
     Similar to the system  100 , the system  300  converts the baseband to the radio frequency band (and back) in two steps: once from the baseband to the intermediate frequency and once from the intermediate frequency to radio frequency. The intermediate frequency used does not require a high level of bandwidth, as compared to previous systems, as the integrated modem  302  is located nearby the antenna device  314 , and lengthy intermediate frequency cable runs are not used. By having the various components of the system located proximal to the antenna device  314 , the system is made more efficient, more compact, cheaper to produce, easier to maintain, and lighter. 
     Similar to the systems  100  and  200 , the application of the user data transmission may be digitally configured and adjusted without modifying the physical components of the system  300 . For example, the user data may be transmitted using satellite communications or may be transmitted using terrestrial communications by configuring the transmit tuner  306 , which includes an adjustable, agile local oscillator configured to provide any number of different waveforms. Thus, the system  300  is not limited to one type of communications. Accordingly, the receive tuner  308  also may have an adjustable, agile local oscillator. In some embodiments, as shown in  FIG.  3   , the transmit tuner  306  and the receive tuner  308  also include a mixer and a bandpass filter. 
       FIG.  4    illustrates an example embodiment of the fully integrated radio frequency terminal system, according to an embodiment of the present disclosure. The system  400  is similar to the system  100 , the system  200 , and the system  300 , and like parts are numbered similarly. 
     The system  400  includes an integrated modem  402 , a power amplifier  410 , a low noise amplifier  412 , and an antenna device  414 . The integrated modem  402 , the power amplifier  410 , and the low noise amplifier  412  may be physically located proximal to the antenna device  414 . As described herein, this is different from a conventional system, where a modem is located proximal to the user device, a radio frequency assembly is located proximal to the antenna device, and intermediate frequency cables are run between the modem and the radio frequency assembly. 
     In some embodiments, the integrated modem  402 , the power amplifier  410 , and the low noise amplifier  412  are within a single housing. In other embodiments, the integrated modem  402  is within a first housing and the power amplifier  410  and the low noise amplifier  412  are within a second housing. In some embodiments, some or all of the antenna device  414  is in the same housing as the integrated modem  402 . 
     The integrated modem  402  includes a baseband modem device  404  configured to receive a baseband signal of user data and transmit a baseband signal of user data. The user data may be sent to the integrated modem  402  via a digital interface cable, which does not affect transmission performance. While digital interface cables are described as being used herein, any digital link approach, including fiber optics, may be used to communicate user data. 
     The user data  416  from a plurality of user devices may be received by a port expander  424 . The port expander  424  may receive a plurality of data streams and transmit the plurality of data streams as a single data stream (e.g., data  426 ) to a single recipient (e.g., the integrated modem  402 ). In addition, the port expander  424  may receive a data stream from a single source (e.g., the integrated modem  402 ) and may separate the data stream into a plurality of data streams (e.g., user data  416 ). By incorporating the port expander  424 , more user devices may have access to the system  400  for transmitting and receiving data. 
     The port expander  424  may be located proximal to the integrated modem  402 , such that the data  426  travels through a relatively short digital interface cable and the user data  416  travels through a relatively long digital interface cable. Alternatively, the port expander  424  may be located away from the integrated modem  402 , such that the data  426  travels through a relatively long digital interface cable. 
     The integrated modem  402  includes a digital predistortion device  420  configured to reduce distortion of the user data  416  as it is processed for transmission by the antenna device  414 . The digital predistortion device  420  receives a sample of the data signal after it is converted to the radio frequency band by the transmit tuner  406  and the power amplifier  410 , and the digital predistortion device  420  compensates for distortion detected in the sample, such that distortion in subsequent data is reduced. 
     The integrated modem  402  also includes a transmit tuner  406  and a receive tuner  408 . The transmit tuner  406  tunes a received, digitally predistorted baseband signal and converts the baseband signal to an intermediate frequency. The intermediate frequency signal is then provided to a power amplifier  410 , which converts the intermediate frequency signal to the radio frequency band signals. The antenna device  314  receives the radio frequency band signals and transmits them via an RF link  418 . 
     The antenna device  414  may receive data via the RF link  318  in the radio frequency band, and the antenna device  414  may provide the received data to the low noise amplifier  412  for converting down to an intermediate frequency. The converted data is provided to the receive tuner  308  for further conversion down to baseband, so that the data can be passed to the user device via the baseband modem device  404 . 
     Similar to the system  100  and the system  300 , the system  400  converts the baseband to the radio frequency band (and back) in two steps: once from the baseband to the intermediate frequency and once from the intermediate frequency to the radio frequency. The intermediate frequency used does not require a high level of bandwidth, as compared to previous systems, as the integrated modem  402  is located nearby the antenna device  414 , and lengthy intermediate frequency cable runs are not used. By having the various components of the system located proximal to the antenna device  414 , the system is made more efficient, more compact, cheaper to produce, easier to maintain, and lighter. 
     Similar to the systems  100 ,  200 , and  300  the application of the user data transmission may be digitally configured and adjusted without modifying the physical components of the system  400 . For example, the user data may be transmitted using satellite communications or may be transmitted using terrestrial communications by configuring the transmit tuner  406 , which includes an adjustable, agile local oscillator configured to provide any number of different waveforms. Thus, the system  400  is not limited to one type of communications. Accordingly, the receive tuner  408  also may have an adjustable, agile local oscillator. In some embodiments, as shown in  FIG.  4   , the transmit tuner  406  and the receive tuner  408  also include a mixer and a bandpass filter. 
     The systems described herein (e.g., the system  100 , the system  200 , the system  300 , and the system  400 ) are usable with any antenna type. 
       FIG.  5    illustrates a flowchart of a process of the integrated radio frequency terminal system. 
     The process  500  begins with an integrated modem (e.g., integrated modem  102 ,  202 ,  302 ,  402 ) receiving user data (e.g., user data  116 ,  216 ,  316 ,  416 ) in baseband frequency (step  502 ). As described herein, the user data may be received from a user device. The user device may be located indoors and the integrated modem may be located outdoors, proximal to the antenna device. 
     A predistortion device (e.g., digital predistortion device  320 ,  420 ) predistorts the user data in baseband frequency (step  504 ). By predistorting the user data, the transmitted radio frequency data may be made clearer. 
     The integrated modem converts the user data from a baseband frequency to a radio frequency (step  506 ). The radio frequency may be in the Ku band or higher. The integrated modem may convert the user data from the baseband frequency to the radio frequency either in one step or in two steps, from the baseband frequency to an intermediate frequency, and from an intermediate frequency to the radio frequency, as described herein. The intermediate frequency may be any frequency between the baseband frequency and the radio frequency. 
     An antenna device (e.g., antenna device  114 ,  214 ,  314 ,  414 ) receives the converted user data (step  508 ). The converted user data is in radio frequency and the antenna device transmits the converted user data (step  510 ). 
     The antenna device may receive incoming data in radio frequency (step  512 ). The antenna device provides the incoming data to the integrated modem (step  514 ). The integrated modem converts the incoming data to the baseband frequency (step  516 ). The integrated modem may convert the incoming data to the baseband frequency in one step or in two steps, from the radio frequency to the intermediate frequency, and from the intermediate frequency to the baseband frequency. The integrated modem then provides the incoming data in the baseband frequency to the user device (step  518 ). 
     Where used throughout the specification and the claims, “at least one of A or B” includes “A” only, “B” only, or “A and B.” Exemplary embodiments of the methods/systems have been disclosed in an illustrative style. Accordingly, the terminology employed throughout should be read in a non-limiting manner. Although minor modifications to the teachings herein will occur to those well versed in the art, it shall be understood that what is intended to be circumscribed within the scope of the patent warranted hereon are all such embodiments that reasonably fall within the scope of the advancement to the art hereby contributed, and that that scope shall not be restricted, except in light of the appended claims and their equivalents.