Abstract:
One or more input signals are used to generate a Pseudo noise generator and re-inject the signal to obtain a more efficient method of control of a receiver using adaptive antenna array technology. The antenna array automatically adjusts its direction to the optimum using information obtained from the input signal by the receiving antenna elements. The input signals may be stored in memory for retrieval, comparison and then used to optimize reception. The difference between the outputs of the memorized signals and the reference signal is used as an error signal. One or multiple Modal antennas, where the Modal antenna is capable of generating several unique radiation patterns, can implement this optimization technique in a MIMO configuration.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation in part (CIP) of U.S. Ser. No. 14/109,789, filed Dec. 13, 2013; 
         [0002]    which is a CON of U.S. patent application Ser. No. 13/548,895, filed Jul. 13, 2012, now U.S. Pat. No. 8,633,863, issued Jan. 21, 2014; 
         [0003]    which is a CIP of U.S. patent application Ser. No. 13/029,564, filed Feb. 17, 2011, and titled “Antenna and Method for Steering Antenna Beam Direction”, now U.S. Pat. No. 8,362,962, issued Jan. 29, 2013; 
         [0004]    which is a CON of U.S. patent application Ser. No. 12/043,090, filed Mar. 5, 2008, and titled “Antenna and Method for Steering Antenna Beam Direction”, now U.S. Pat. No. 7,911,402, issued Mar. 22, 2011; 
         [0005]    the contents of each of which are hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0006]    Field of the Invention 
         [0007]    This invention relates to wireless communication systems, and more particularly, to a modal adaptive antenna system and related signal receiving methods for long term evolution (LTE) networks. 
         [0008]    Description of the Related Art 
         [0009]    In a classical operation of a smart antenna system, the array input vectors are applied to multipliers forming the adaptive array, a summing circuit and an adaptive processor for adjusting the weights. 
         [0010]    The signals are multiplied by weighted outputs from the adaptive processor. It takes a long period of time for the adaptive processor to process the calculations. Additionally, the adaptive processor is complicated. Consequently it is difficult to apply a classical scheme. 
         [0011]    It is generally known in the art that these classical systems require extended periods of time for the adaptive processor to process calculations for signal receiving. Additionally, the circuit of the adaptive processor is complicated, and therefore it is difficult to apply the conventional smart antenna system to LTE mobile communications. 
         [0012]    Modernly, it is therefore a requirement in the dynamic field of mobile communications to provide improved and more efficient methods of signal receiving and processing. Current trends and demand in the industry continue to drive improvements in signal receiving and processing for mobile LTE communications systems. 
       SUMMARY OF THE INVENTION 
       [0013]    A single or multiple input signals are used to generate a Pseudo noise generator and re-inject the signal to obtain a more efficient method of control of a receiver using adaptive antenna array technology. The antenna array automatically adjusts its direction to the optimum using information obtained from the input signal by the receiving antenna elements. The input signals may be stored in memory for retrieval, comparison and then used to optimize reception. The difference between the outputs of the memorized signals and the reference signal is used as an error signal. One or multiple Modal antennas, where the Modal antenna is capable of generating several unique radiation patterns, can implement this optimization technique in a MIMO configuration. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    These and other attributes of the invention are further described in the following detailed description of the invention, particularly when reviewed in conjunction with the drawings, wherein: 
           [0015]      FIG. 1  shows an adaptive antenna system with a circuit block coupled to a comparator, counter, adaptive processor, automatic tuning module and lookup table, wherein the adaptive antenna system is configured to provide voltage signals for controlling active tuning components of a modal antenna for varying a corresponding radiation mode thereof. 
           [0016]      FIG. 2  shows a two-antenna array, each of the antennas includes a modal antenna, wherein each modal antenna is coupled to a circuit block and adaptive processor, each of the respective circuit blocks are illustrated with at least a summing circuit, filter, limiter, code generator. 
           [0017]      FIG. 3  shows a two-antenna array, each of the antennas includes a modal antenna, wherein each modal antenna is coupled to a circuit block, and each circuit block is coupled to a shared adaptive processor. 
           [0018]      FIG. 4  shows a multi-input multi-output (MIMO) antenna processing system for providing voltage signals to active tuning components of a modal antenna. 
           [0019]      FIG. 5  shows up to “N” modal antennas and “N” circuit blocks can be combined with an adaptive processor to provide an N-element antenna array. 
           [0020]      FIG. 6  shows a modal antenna including a main antenna element (radiating element) and two parasitic elements each coupled to a corresponding active tuning component, wherein voltages are used to alter a state of the active tuning components and associated parasitic elements. 
           [0021]      FIG. 7  shows a process for optimizing the antenna system. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    In the following description, for purposes of explanation and not limitation, details and descriptions are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments that depart from these details and descriptions. 
         [0023]    A multimode antenna, or “modal antenna”, is described in commonly owned U.S. Pat. No. 7,911,402, issued Mar. 22, 2011, hereinafter referred to as the “&#39;402 patent”, the contents of which are incorporated by reference. The modal antenna of the &#39;402 patent generally comprises an isolated magnetic dipole (IMD) element having one or more resonance portions thereof disposed above a circuit board to form a volume of the antenna. A first parasitic element is positioned between the IMD element and the circuit board within the volume of the antenna. A second parasitic element is positioned adjacent to the IMD element but outside of the antenna volume. Due to proximity of these parasitic elements and other factors, the first parasitic element is adapted to shift a frequency response of the antenna to actively tune one or more of the antenna resonance portions, and the second parasitic element is adapted to steer the antenna beam. In sum, the modal antenna of the &#39;402 patent is capable of frequency shifting and beam steering. Moreover, where the antenna beam comprises a null, the null can be similarly steered such that the antenna can be said to be capable of null steering. For purposes of illustration, the modal antenna of the &#39;402 patent provides a suitable example for use in the invention; however, it will be understood that other modal antennas may be used with some variation to the embodiments described herein. 
         [0024]    Now turning to the drawings,  FIG. 1  shows an antenna circuit (Block A is detailed in  FIG. 2 ). An output S 11 - 1  from Block A is compared with voltage reference signal V ref  at comparator  112 . The output of the comparator  112  increments or decrements a counter  113  based upon the comparator  112  output. The counter output signal S 11 - 2  in conjunction with an output S 11 - 3  from the adaptive processor  111 , and a bi-directional signal S 11 - 4   a  from the automatic tuning module  115 , determine the output required from the look-up table  114 . This resultant signal S 11 - 4   b  in conjunction with signal S 11 - 5  from the adaptive processor  111  are used to determine the outputs V 1  and V 2  from the automatic tuning module  115 . See  FIG. 6  for the physical representation of the application of V 1  and V 2 . 
         [0025]      FIG. 2  shows a modal antenna system for LTE communication, modal antenna  1  is coupled to Block A, and the combination provides “n” modes for use with the Block A circuit and the adaptive processor  1 . A second modal antenna, Modal antenna  2 , is shown coupled to a Block B and also provides “n” modes for use with the Block B circuit and adaptive processor  2 . Note that “n” modes means any integer greater than one. This two-antenna system can be used in a MIMO antenna configuration. 
         [0026]      FIG. 3  illustrates another embodiment where a first modal antenna “Modal antenna  1 ” is coupled to circuit Block A and the combination provides “n” Modes for use with the Block A circuit. Modal antenna  2  is coupled to Block B and provides “n” modes for use with the Block B circuit. A common adaptive processor is used with the two-antenna configuration. One of the modes from Modal antenna  1  can be used as a reference signal for optimizing Modal antenna  2 , and/or one of the Modes from Modal antenna  2  can be used to optimize Modal antenna  1 . This two-antenna system can be used in a MIMO antenna configuration. 
         [0027]      FIG. 4  illustrates a multi-antenna Modal adaptive system. One or more inputs Ai are coupled to the Block A circuit and one or more inputs Bi are coupled to Block B circuit. The inputs Ai and Bi can be supplied by a Modal antenna. 
         [0028]    One of the inputs Ai are used as a reference signal and fed to a comparator and compared with voltage reference signal V ref  at first comparator  112 . The output of the comparator  112  increments or decrements a counter  113  based upon the comparator  112  output. The counter output signal S 11 - 2  in conjunction with an output S 11 - 3  from the adaptive processor  111  and a bi-directional signal S 11 - 4   a  from the automatic tuning module  115  determine the output required from the look-up table  114 . This resultant signal  11 - 4   b  in conjunction with signal S 11 - 5  from the Adaptive Processor  111  are used to determine the outputs V 1  and V 2  from the automatic tuning module  115 . See  FIG. 6  for the physical representation of the application of V 1  and V 2 . 
         [0029]    One of the inputs Bi are used as a reference signal and fed to a second comparator and compared with voltage reference signal V ref  at second comparator  122 . The output of the second comparator  122  increments or decrements a second counter  123  based upon the second comparator  122  output. The second counter output signal S 21 - 2  in conjunction with an output S 21 - 3  from the adaptive processor  111  and a second bi-directional signal S 21 - 4   a  from the second automatic tuning module  125  determine the second output required from the second look-up table  124 . This resultant signal  21 - 4   b  in conjunction with signal S 21 - 5  from the adaptive processor  111  are used to determine the outputs V 3  and V 4  from the second automatic tuning module  125 . See  FIG. 6  for the physical representation of the application of V 3  and V 4 . 
         [0030]      FIG. 5  shows an embodiment implementing “n” Modal antennas coupled to N Block circuits, respectively, with all Modal antenna/Block circuits controlled by a single adaptive processor, thereby forming an “n” Modal antenna array. 
         [0031]      FIG. 6  illustrates an exemplary physical example of a Modal antenna with voltages V 1  and V 2  applied to parasitic elements  1  and  2  used to modify the angle of maxima and/or minima of the radiation pattern (or any other parameters driving the antenna performance) for the Main Antenna  1  (radiating element) as shown for Mode  1  through Mode N. The voltages V 1  and V 2  are derived from a look-up table and are generated based upon changes in the input signals utilizing the methods described herein. 
         [0032]      FIG. 7  illustrates a flow diagram describing the process of sampling the response from the multiple antenna modes and developing weights for each mode. A pilot signal  70  is received when the antenna mode  71  is set to the first mode. A second pilot signal  72  is sampled with the antenna set to the second mode  73  and this process is repeated until all modes have been sampled. An estimation of antenna performance that occurs between sampled modes  74  is made. Weights are evaluated for the processor  75  based upon the sampled antenna responses for the various modes n. The adaptive process is highlighted starting in  70   a  where a pilot signal is received for antenna mode  1   71   a.  The receive response is stored and compared to previous received responses for mode  1  and estimates are made for receive response for the other antenna modes  72   a  and  73   a.  An estimate of antenna performance between sampled modes is performed  74   a.  Weights are evaluated for the processor  75   a  based on the sampled and estimated antenna response for the modes. 
         [0033]    While the invention has been shown and described with reference to one or more certain preferred embodiments thereof, it will be understood by those having skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.